diff --git a/src/app/Console/Development/TemplateRender.php b/src/app/Console/Development/TemplateRender.php
--- a/src/app/Console/Development/TemplateRender.php
+++ b/src/app/Console/Development/TemplateRender.php
@@ -11,7 +11,7 @@
      *
      * @var string
      */
-    protected $signature = 'template:render {template} {--html} {--pdf}';
+    protected $signature = 'template:render {template} {--html} {--text} {--pdf}';
 
     /**
      * The console command description.
@@ -52,6 +52,8 @@
         $mode = 'html';
         if (!empty($this->option('pdf'))) {
             $mode = 'pdf';
+        } elseif (!empty($this->option('text'))) {
+            $mode = 'text';
         }
 
         echo $class::fakeRender($mode);
diff --git a/src/app/Documents/Receipt.php b/src/app/Documents/Receipt.php
--- a/src/app/Documents/Receipt.php
+++ b/src/app/Documents/Receipt.php
@@ -42,6 +42,8 @@
     /**
      * Render the mail template with fake data
      *
+     * @param string $type Output format ('html' or 'pdf')
+     *
      * @return string HTML or PDF output
      */
     public static function fakeRender(string $type = 'html'): string
@@ -56,6 +58,8 @@
 
         if ($type == 'pdf') {
             return $receipt->pdfOutput();
+        } elseif ($type !== 'html') {
+            throw new \Exception("Unsupported output format");
         }
 
         return $receipt->htmlOutput();
diff --git a/src/app/Mail/Helper.php b/src/app/Mail/Helper.php
new file mode 100644
--- /dev/null
+++ b/src/app/Mail/Helper.php
@@ -0,0 +1,33 @@
+<?php
+
+namespace App\Mail;
+
+use Illuminate\Mail\Mailable;
+
+class Helper
+{
+    /**
+     * Render the mail template.
+     *
+     * @param \Illuminate\Mail\Mailable $mail The mailable object
+     * @param string $type Output format ('html' or 'text')
+     *
+     * @return string HTML or Plain Text output
+     */
+    public static function render(Mailable $mail, string $type = 'html'): string
+    {
+        // Plain text output
+        if ($type == 'text') {
+            $mail->build(); // @phpstan-ignore-line
+
+            $mailer = \Illuminate\Container\Container::getInstance()->make('mailer');
+
+            return $mailer->render(['text' => $mail->textView], $mail->buildViewData());
+        } elseif ($type != 'html') {
+            throw new \Exception("Unsupported output format");
+        }
+
+        // HTML output
+        return $mail->build()->render(); // @phpstan-ignore-line
+    }
+}
diff --git a/src/app/Mail/NegativeBalance.php b/src/app/Mail/NegativeBalance.php
--- a/src/app/Mail/NegativeBalance.php
+++ b/src/app/Mail/NegativeBalance.php
@@ -40,7 +40,8 @@
 
         $subject = \trans('mail.negativebalance-subject', ['site' => \config('app.name')]);
 
-        $this->view('emails.negative_balance')
+        $this->view('emails.html.negative_balance')
+            ->text('emails.plain.negative_balance')
             ->subject($subject)
             ->with([
                     'site' => \config('app.name'),
@@ -56,14 +57,16 @@
     /**
      * Render the mail template with fake data
      *
-     * @return string HTML output
+     * @param string $type Output format ('html' or 'text')
+     *
+     * @return string HTML or Plain Text output
      */
-    public static function fakeRender(): string
+    public static function fakeRender(string $type = 'html'): string
     {
         $user = new User();
 
         $mail = new self($user);
 
-        return $mail->build()->render();
+        return Helper::render($mail, $type);
     }
 }
diff --git a/src/app/Mail/PasswordReset.php b/src/app/Mail/PasswordReset.php
--- a/src/app/Mail/PasswordReset.php
+++ b/src/app/Mail/PasswordReset.php
@@ -42,7 +42,8 @@
             sprintf('/login/reset/%s-%s', $this->code->short_code, $this->code->code)
         );
 
-        $this->view('emails.password_reset')
+        $this->view('emails.html.password_reset')
+            ->text('emails.plain.password_reset')
             ->subject(__('mail.passwordreset-subject', ['site' => \config('app.name')]))
             ->with([
                     'site' => \config('app.name'),
@@ -58,9 +59,11 @@
     /**
      * Render the mail template with fake data
      *
-     * @return string HTML output
+     * @param string $type Output format ('html' or 'text')
+     *
+     * @return string HTML or Plain Text output
      */
-    public static function fakeRender(): string
+    public static function fakeRender(string $type = 'html'): string
     {
         $code = new VerificationCode([
                 'code' => Str::random(VerificationCode::CODE_LENGTH),
@@ -73,6 +76,6 @@
 
         $mail = new self($code);
 
-        return $mail->build()->render();
+        return Helper::render($mail, $type);
     }
 }
diff --git a/src/app/Mail/PaymentFailure.php b/src/app/Mail/PaymentFailure.php
--- a/src/app/Mail/PaymentFailure.php
+++ b/src/app/Mail/PaymentFailure.php
@@ -46,7 +46,8 @@
 
         $subject = \trans('mail.paymentfailure-subject', ['site' => \config('app.name')]);
 
-        $this->view('emails.payment_failure')
+        $this->view('emails.html.payment_failure')
+            ->text('emails.plain.payment_failure')
             ->subject($subject)
             ->with([
                     'site' => \config('app.name'),
@@ -62,21 +63,19 @@
     /**
      * Render the mail template with fake data
      *
-     * @return string HTML output
+     * @param string $type Output format ('html' or 'text')
+     *
+     * @return string HTML or Plain Text output
      */
-    public static function fakeRender(): string
+    public static function fakeRender(string $type = 'mail'): string
     {
         $payment = new Payment();
         $user = new User([
               'email' => 'test@' . \config('app.domain'),
         ]);
 
-        if (!\config('app.support_url')) {
-            \config(['app.support_url' => 'https://not-configured-support.url']);
-        }
-
         $mail = new self($payment, $user);
 
-        return $mail->build()->render();
+        return Helper::render($mail, $type);
     }
 }
diff --git a/src/app/Mail/PaymentMandateDisabled.php b/src/app/Mail/PaymentMandateDisabled.php
--- a/src/app/Mail/PaymentMandateDisabled.php
+++ b/src/app/Mail/PaymentMandateDisabled.php
@@ -46,7 +46,8 @@
 
         $subject = \trans('mail.paymentmandatedisabled-subject', ['site' => \config('app.name')]);
 
-        $this->view('emails.payment_mandate_disabled')
+        $this->view('emails.html.payment_mandate_disabled')
+            ->text('emails.plain.payment_mandate_disabled')
             ->subject($subject)
             ->with([
                     'site' => \config('app.name'),
@@ -62,21 +63,19 @@
     /**
      * Render the mail template with fake data
      *
-     * @return string HTML output
+     * @param string $type Output format ('html' or 'text')
+     *
+     * @return string HTML or Plain Text output
      */
-    public static function fakeRender(): string
+    public static function fakeRender(string $type = 'html'): string
     {
         $wallet = new Wallet();
         $user = new User([
               'email' => 'test@' . \config('app.domain'),
         ]);
 
-        if (!\config('app.support_url')) {
-            \config(['app.support_url' => 'https://not-configured-support.url']);
-        }
-
         $mail = new self($wallet, $user);
 
-        return $mail->build()->render();
+        return Helper::render($mail, $type);
     }
 }
diff --git a/src/app/Mail/PaymentSuccess.php b/src/app/Mail/PaymentSuccess.php
--- a/src/app/Mail/PaymentSuccess.php
+++ b/src/app/Mail/PaymentSuccess.php
@@ -46,7 +46,8 @@
 
         $subject = \trans('mail.paymentsuccess-subject', ['site' => \config('app.name')]);
 
-        $this->view('emails.payment_success')
+        $this->view('emails.html.payment_success')
+            ->text('emails.plain.payment_success')
             ->subject($subject)
             ->with([
                     'site' => \config('app.name'),
@@ -62,21 +63,19 @@
     /**
      * Render the mail template with fake data
      *
-     * @return string HTML output
+     * @param string $type Output format ('html' or 'text')
+     *
+     * @return string HTML or Plain Text output
      */
-    public static function fakeRender(): string
+    public static function fakeRender(string $type = 'html'): string
     {
         $payment = new Payment();
         $user = new User([
               'email' => 'test@' . \config('app.domain'),
         ]);
 
-        if (!\config('app.support_url')) {
-            \config(['app.support_url' => 'https://not-configured-support.url']);
-        }
-
         $mail = new self($payment, $user);
 
-        return $mail->build()->render();
+        return Helper::render($mail, $type);
     }
 }
diff --git a/src/app/Mail/SignupVerification.php b/src/app/Mail/SignupVerification.php
--- a/src/app/Mail/SignupVerification.php
+++ b/src/app/Mail/SignupVerification.php
@@ -47,14 +47,15 @@
         }
         $username = trim($username);
 
-        $this->view('emails.signup_code')
+        $this->view('emails.html.signup_code')
+            ->text('emails.plain.signup_code')
             ->subject(__('mail.signupcode-subject', ['site' => \config('app.name')]))
             ->with([
                     'site' => \config('app.name'),
                     'username' => $username ?: 'User',
                     'code' => $this->code->code,
                     'short_code' => $this->code->short_code,
-                    'link' => sprintf('<a href="%s">%s</a>', $href, $href),
+                    'href' => $href,
             ]);
 
         return $this;
@@ -63,9 +64,11 @@
     /**
      * Render the mail template with fake data
      *
-     * @return string HTML output
+     * @param string $type Output format ('html' or 'text')
+     *
+     * @return string HTML or Plain Text output
      */
-    public static function fakeRender(): string
+    public static function fakeRender(string $type = 'html'): string
     {
         $code = new SignupCode([
                 'code' => Str::random(SignupCode::CODE_LENGTH),
@@ -77,9 +80,8 @@
                 ],
         ]);
 
-
         $mail = new self($code);
 
-        return $mail->build()->render();
+        return Helper::render($mail, $type);
     }
 }
diff --git a/src/app/Mail/SuspendedDebtor.php b/src/app/Mail/SuspendedDebtor.php
--- a/src/app/Mail/SuspendedDebtor.php
+++ b/src/app/Mail/SuspendedDebtor.php
@@ -40,12 +40,15 @@
 
         $subject = \trans('mail.suspendeddebtor-subject', ['site' => \config('app.name')]);
 
-        $moreInfo = null;
+        $moreInfoHtml = null;
+        $moreInfoText = null;
         if ($moreInfoUrl = \config('app.kb.account_suspended')) {
-            $moreInfo = \trans('mail.more-info-html', ['href' => $moreInfoUrl]);
+            $moreInfoHtml = \trans('mail.more-info-html', ['href' => $moreInfoUrl]);
+            $moreInfoText = \trans('mail.more-info-text', ['href' => $moreInfoUrl]);
         }
 
-        $this->view('emails.suspended_debtor')
+        $this->view('emails.html.suspended_debtor')
+            ->text('emails.plain.suspended_debtor')
             ->subject($subject)
             ->with([
                     'site' => \config('app.name'),
@@ -54,7 +57,8 @@
                     'cancelUrl' => \config('app.kb.account_delete'),
                     'supportUrl' => \config('app.support_url'),
                     'walletUrl' => Utils::serviceUrl('/wallet'),
-                    'moreInfo' => $moreInfo,
+                    'moreInfoHtml' => $moreInfoHtml,
+                    'moreInfoText' => $moreInfoText,
                     'days' => 14 // TODO: Configurable
             ]);
 
@@ -64,26 +68,16 @@
     /**
      * Render the mail template with fake data
      *
-     * @return string HTML output
+     * @param string $type Output format ('html' or 'text')
+     *
+     * @return string HTML or Plain Text output
      */
-    public static function fakeRender(): string
+    public static function fakeRender(string $type = 'html'): string
     {
         $user = new User();
 
-        if (!\config('app.support_url')) {
-            \config(['app.support_url' => 'https://not-configured-support.url']);
-        }
-
-        if (!\config('app.kb.account_delete')) {
-            \config(['app.kb.account_delete' => 'https://not-configured-kb.url']);
-        }
-
-        if (!\config('app.kb.account_suspended')) {
-            \config(['app.kb.account_suspended' => 'https://not-configured-kb.url']);
-        }
-
         $mail = new self($user);
 
-        return $mail->build()->render();
+        return Helper::render($mail, $type);
     }
 }
diff --git a/src/composer.json b/src/composer.json
--- a/src/composer.json
+++ b/src/composer.json
@@ -22,7 +22,7 @@
         "iatstuti/laravel-nullable-fields": "*",
         "kolab/net_ldap3": "dev-master",
         "laravel/framework": "6.*",
-        "laravel/tinker": "^1.0",
+        "laravel/tinker": "^2.4",
         "mollie/laravel-mollie": "^2.9",
         "morrislaptop/laravel-queue-clear": "^1.2",
         "silviolleite/laravelpwa": "^1.0",
@@ -39,10 +39,11 @@
         "beyondcode/laravel-er-diagram-generator": "^1.3",
         "filp/whoops": "^2.0",
         "fzaninotto/faker": "^1.4",
+        "kirschbaum-development/mail-intercept": "^0.2.4",
         "laravel/dusk": "~5.11.0",
         "mockery/mockery": "^1.0",
         "nunomaduro/larastan": "^0.5",
-        "phpstan/phpstan": "^0.12",
+        "phpstan/phpstan": "0.12.25",
         "phpunit/phpunit": "^8"
     },
     "config": {
diff --git a/src/resources/lang/en/mail.php b/src/resources/lang/en/mail.php
--- a/src/resources/lang/en/mail.php
+++ b/src/resources/lang/en/mail.php
@@ -14,11 +14,12 @@
     'footer' => "Best regards,\nYour :site Team",
 
     'more-info-html' => "See <a href=\":href\">here</a> for more information.",
+    'more-info-text' => "See :href for more information.",
 
     'negativebalance-subject' => ":site Payment Reminder",
     'negativebalance-body' => "It has probably skipped your attention that you are behind on paying for your :site account. "
-        . "Consider setting up auto-payment to avoid messages like this in the future.\n\n"
-        . "Settle up to keep your account running.",
+        . "Consider setting up auto-payment to avoid messages like this in the future.",
+    'negativebalance-body-extd' => "Settle up to keep your account running.",
 
     'passwordreset-subject' => ":site Password Reset",
     'passwordreset-body' => "Someone recently asked to change your :site password.\n"
@@ -29,16 +30,16 @@
     'paymentmandatedisabled-subject' => ":site Auto-payment Problem",
     'paymentmandatedisabled-body' => "Your :site account balance is negative "
         . "and the configured amount for automatically topping up the balance does not cover "
-        . "the costs of subscriptions consumed.\n\n"
-        . "Charging you multiple times for the same amount in short succession "
+        . "the costs of subscriptions consumed.",
+    'paymentmandatedisabled-body-ext' => "Charging you multiple times for the same amount in short succession "
         . "could lead to issues with the payment provider. "
         . "In order to not cause any problems, we suspended auto-payment for your account. "
         . "To resolve this issue, login to your account settings and adjust your auto-payment amount.",
 
     'paymentfailure-subject' => ":site Payment Failed",
     'paymentfailure-body' => "Something went wrong with auto-payment for your :site account.\n"
-        . "We tried to charge you via your preferred payment method, but the charge did not go through.\n\n"
-        . "In order to not cause any further issues, we suspended auto-payment for your account. "
+        . "We tried to charge you via your preferred payment method, but the charge did not go through.",
+    'paymentfailure-body-ext' => "In order to not cause any further issues, we suspended auto-payment for your account. "
         . "To resolve this issue, login to your account settings at",
     'paymentfailure-body-rest' => "There you can pay manually for your account and "
         . "change your auto-payment settings.",
@@ -47,8 +48,8 @@
     'paymentsuccess-body' => "The auto-payment for your :site account went through without issues. "
         . "You can check your new account balance and more details here:",
 
-    'support' => "Special circumstances? Something wrong with a charge?\n"
-        . " :site Support is here to help:",
+    'support' => "Special circumstances? Something is wrong with a charge?\n"
+        . ":site Support is here to help.",
 
     'signupcode-subject' => ":site Registration",
     'signupcode-body' => "This is your verification code for the :site registration process: :code.\n"
diff --git a/src/resources/views/documents/receipt.blade.php b/src/resources/views/documents/receipt.blade.php
--- a/src/resources/views/documents/receipt.blade.php
+++ b/src/resources/views/documents/receipt.blade.php
@@ -3,7 +3,7 @@
     <head>
         <meta charset="utf-8">
         <style>
-{!! include('public/css/document.css') !!}
+<?php include public_path('css/document.css') ?>
         </style>
     </head>
     <body>
diff --git a/src/resources/views/emails/negative_balance.blade.php b/src/resources/views/emails/html/negative_balance.blade.php
rename from src/resources/views/emails/negative_balance.blade.php
rename to src/resources/views/emails/html/negative_balance.blade.php
--- a/src/resources/views/emails/negative_balance.blade.php
+++ b/src/resources/views/emails/html/negative_balance.blade.php
@@ -7,6 +7,7 @@
         <p>{{ __('mail.header', ['name' => $username]) }}</p>
 
         <p>{{ __('mail.negativebalance-body', ['site' => $site]) }}</p>
+        <p>{{ __('mail.negativebalance-body-ext', ['site' => $site]) }}</p>
         <p><a href="{{ $walletUrl }}">{{ $walletUrl }}</a></p>
 
 @if ($supportUrl)
@@ -14,6 +15,6 @@
         <p><a href="{{ $supportUrl }}">{{ $supportUrl }}</a></p>
 @endif
 
-        <p>{{ __('mail.footer', ['site' => $site, 'appurl' => config('app.url')]) }}</p>
+        <p>{{ __('mail.footer', ['site' => $site]) }}</p>
     </body>
 </html>
diff --git a/src/resources/views/emails/password_reset.blade.php b/src/resources/views/emails/html/password_reset.blade.php
rename from src/resources/views/emails/password_reset.blade.php
rename to src/resources/views/emails/html/password_reset.blade.php
--- a/src/resources/views/emails/password_reset.blade.php
+++ b/src/resources/views/emails/html/password_reset.blade.php
@@ -10,6 +10,6 @@
 
         <p>{!! $link !!}</p>
 
-        <p>{{ __('mail.footer', ['site' => $site, 'appurl' => config('app.url')]) }}</p>
+        <p>{{ __('mail.footer', ['site' => $site]) }}</p>
     </body>
 </html>
diff --git a/src/resources/views/emails/payment_failure.blade.php b/src/resources/views/emails/html/payment_failure.blade.php
rename from src/resources/views/emails/payment_failure.blade.php
rename to src/resources/views/emails/html/payment_failure.blade.php
--- a/src/resources/views/emails/payment_failure.blade.php
+++ b/src/resources/views/emails/html/payment_failure.blade.php
@@ -7,6 +7,7 @@
         <p>{{ __('mail.header', ['name' => $username]) }}</p>
 
         <p>{{ __('mail.paymentfailure-body', ['site' => $site]) }}</p>
+        <p>{{ __('mail.paymentfailure-body-ext', ['site' => $site]) }}</p>
         <p><a href="{{ $walletUrl }}">{{ $walletUrl }}</a></p>
         <p>{{ __('mail.paymentfailure-body-rest', ['site' => $site]) }}</p>
 
@@ -15,6 +16,6 @@
         <p><a href="{{ $supportUrl }}">{{ $supportUrl }}</a></p>
 @endif
 
-        <p>{{ __('mail.footer', ['site' => $site, 'appurl' => config('app.url')]) }}</p>
+        <p>{{ __('mail.footer', ['site' => $site]) }}</p>
     </body>
 </html>
diff --git a/src/resources/views/emails/payment_mandate_disabled.blade.php b/src/resources/views/emails/html/payment_mandate_disabled.blade.php
rename from src/resources/views/emails/payment_mandate_disabled.blade.php
rename to src/resources/views/emails/html/payment_mandate_disabled.blade.php
--- a/src/resources/views/emails/payment_mandate_disabled.blade.php
+++ b/src/resources/views/emails/html/payment_mandate_disabled.blade.php
@@ -7,6 +7,7 @@
         <p>{{ __('mail.header', ['name' => $username]) }}</p>
 
         <p>{{ __('mail.paymentmandatedisabled-body', ['site' => $site]) }}</p>
+        <p>{{ __('mail.paymentmandatedisabled-body-ext', ['site' => $site]) }}</p>
         <p><a href="{{ $walletUrl }}">{{ $walletUrl }}</a></p>
         <p>{{ __('mail.paymentfailure-body-rest', ['site' => $site]) }}</p>
 
@@ -15,6 +16,6 @@
         <p><a href="{{ $supportUrl }}">{{ $supportUrl }}</a></p>
 @endif
 
-        <p>{{ __('mail.footer', ['site' => $site, 'appurl' => config('app.url')]) }}</p>
+        <p>{{ __('mail.footer', ['site' => $site]) }}</p>
     </body>
 </html>
diff --git a/src/resources/views/emails/payment_success.blade.php b/src/resources/views/emails/html/payment_success.blade.php
rename from src/resources/views/emails/payment_success.blade.php
rename to src/resources/views/emails/html/payment_success.blade.php
--- a/src/resources/views/emails/payment_success.blade.php
+++ b/src/resources/views/emails/html/payment_success.blade.php
@@ -14,6 +14,6 @@
         <p><a href="{{ $supportUrl }}">{{ $supportUrl }}</a></p>
 @endif
 
-        <p>{{ __('mail.footer', ['site' => $site, 'appurl' => config('app.url')]) }}</p>
+        <p>{{ __('mail.footer', ['site' => $site]) }}</p>
     </body>
 </html>
diff --git a/src/resources/views/emails/signup_code.blade.php b/src/resources/views/emails/html/signup_code.blade.php
rename from src/resources/views/emails/signup_code.blade.php
rename to src/resources/views/emails/html/signup_code.blade.php
--- a/src/resources/views/emails/signup_code.blade.php
+++ b/src/resources/views/emails/html/signup_code.blade.php
@@ -8,8 +8,8 @@
 
         <p>{{ __('mail.signupcode-body', ['code' => $short_code, 'site' => $site]) }}</p>
 
-        <p>{!! $link !!}</p>
+        <p><a href="{!! $href !!}">{!! $href !!}</a></p>
 
-        <p>{{ __('mail.footer', ['site' => $site, 'appurl' => config('app.url')]) }}</p>
+        <p>{{ __('mail.footer', ['site' => $site]) }}</p>
     </body>
 </html>
diff --git a/src/resources/views/emails/suspended_debtor.blade.php b/src/resources/views/emails/html/suspended_debtor.blade.php
rename from src/resources/views/emails/suspended_debtor.blade.php
rename to src/resources/views/emails/html/suspended_debtor.blade.php
--- a/src/resources/views/emails/suspended_debtor.blade.php
+++ b/src/resources/views/emails/html/suspended_debtor.blade.php
@@ -6,7 +6,7 @@
     <body>
         <p>{{ __('mail.header', ['name' => $username]) }}</p>
 
-        <p>{{ __('mail.suspendeddebtor-body', ['site' => $site, 'days' => $days]) }} {!! $moreInfo !!}</p>
+        <p>{{ __('mail.suspendeddebtor-body', ['site' => $site, 'days' => $days]) }} {!! $moreInfoHtml !!}</p>
         <p>{{ __('mail.suspendeddebtor-middle') }}</p>
         <p><a href="{{ $walletUrl }}">{{ $walletUrl }}</a></p>
 
@@ -19,6 +19,6 @@
         <p><a href="{{ $cancelUrl }}">{{ $cancelUrl }}</a></p>
 @endif
 
-        <p>{{ __('mail.footer', ['site' => $site, 'appurl' => config('app.url')]) }}</p>
+        <p>{{ __('mail.footer', ['site' => $site]) }}</p>
     </body>
 </html>
diff --git a/src/resources/views/emails/plain/negative_balance.blade.php b/src/resources/views/emails/plain/negative_balance.blade.php
new file mode 100644
--- /dev/null
+++ b/src/resources/views/emails/plain/negative_balance.blade.php
@@ -0,0 +1,16 @@
+{!! __('mail.header', ['name' => $username]) !!}
+
+{!! __('mail.negativebalance-body', ['site' => $site]) !!}
+
+{!! __('mail.negativebalance-body-ext', ['site' => $site]) !!}
+
+{!! $walletUrl !!}
+
+@if ($supportUrl)
+{!! __('mail.support', ['site' => $site]) !!}
+
+{!! $supportUrl !!}
+@endif
+
+-- 
+{!! __('mail.footer', ['site' => $site]) !!}
diff --git a/src/resources/views/emails/plain/password_reset.blade.php b/src/resources/views/emails/plain/password_reset.blade.php
new file mode 100644
--- /dev/null
+++ b/src/resources/views/emails/plain/password_reset.blade.php
@@ -0,0 +1,8 @@
+{!! __('mail.header', ['name' => $username]) !!}
+
+{!! __('mail.passwordreset-body', ['code' => $short_code, 'site' => $site]) !!}
+
+{!! $link !!}
+
+-- 
+{!! __('mail.footer', ['site' => $site]) !!}
diff --git a/src/resources/views/emails/plain/payment_failure.blade.php b/src/resources/views/emails/plain/payment_failure.blade.php
new file mode 100644
--- /dev/null
+++ b/src/resources/views/emails/plain/payment_failure.blade.php
@@ -0,0 +1,18 @@
+{!! __('mail.header', ['name' => $username]) !!}
+
+{!! __('mail.paymentfailure-body', ['site' => $site]) !!}
+
+{!! __('mail.paymentfailure-body-ext', ['site' => $site]) !!}
+
+{!! $walletUrl !!}
+
+{!! __('mail.paymentfailure-body-rest', ['site' => $site]) !!}
+
+@if ($supportUrl)
+{!! __('mail.support', ['site' => $site]) !!}
+
+{!! $supportUrl !!}
+@endif
+
+-- 
+{!! __('mail.footer', ['site' => $site]) !!}
diff --git a/src/resources/views/emails/plain/payment_mandate_disabled.blade.php b/src/resources/views/emails/plain/payment_mandate_disabled.blade.php
new file mode 100644
--- /dev/null
+++ b/src/resources/views/emails/plain/payment_mandate_disabled.blade.php
@@ -0,0 +1,18 @@
+{!! __('mail.header', ['name' => $username]) !!}
+
+{!! __('mail.paymentmandatedisabled-body', ['site' => $site]) !!}
+
+{!! __('mail.paymentmandatedisabled-body-ext', ['site' => $site]) !!}
+
+{!! $walletUrl !!}
+
+{!! __('mail.paymentfailure-body-rest', ['site' => $site]) !!}
+
+@if ($supportUrl)
+{!! __('mail.support', ['site' => $site]) !!}
+
+{!! $supportUrl !!}
+@endif
+
+-- 
+{!! __('mail.footer', ['site' => $site]) !!}
diff --git a/src/resources/views/emails/plain/payment_success.blade.php b/src/resources/views/emails/plain/payment_success.blade.php
new file mode 100644
--- /dev/null
+++ b/src/resources/views/emails/plain/payment_success.blade.php
@@ -0,0 +1,14 @@
+{!! __('mail.header', ['name' => $username]) !!}
+
+{!! __('mail.paymentsuccess-body', ['site' => $site]) !!}
+
+{!! $walletUrl !!}
+
+@if ($supportUrl)
+{!! __('mail.support', ['site' => $site]) !!}
+
+{!! $supportUrl !!}
+@endif
+
+-- 
+{!! __('mail.footer', ['site' => $site]) !!}
diff --git a/src/resources/views/emails/plain/signup_code.blade.php b/src/resources/views/emails/plain/signup_code.blade.php
new file mode 100644
--- /dev/null
+++ b/src/resources/views/emails/plain/signup_code.blade.php
@@ -0,0 +1,8 @@
+{!! __('mail.header', ['name' => $username]) !!}
+
+{!! __('mail.signupcode-body', ['code' => $short_code, 'site' => $site]) !!}
+
+{!! $href !!}
+
+-- 
+{!! __('mail.footer', ['site' => $site]) !!}
diff --git a/src/resources/views/emails/plain/suspended_debtor.blade.php b/src/resources/views/emails/plain/suspended_debtor.blade.php
new file mode 100644
--- /dev/null
+++ b/src/resources/views/emails/plain/suspended_debtor.blade.php
@@ -0,0 +1,22 @@
+{!! __('mail.header', ['name' => $username]) !!}
+
+{!! __('mail.suspendeddebtor-body', ['site' => $site, 'days' => $days]) !!} {!! $moreInfoText !!}
+
+{!! __('mail.suspendeddebtor-middle') !!}
+
+{!! $walletUrl !!}
+
+@if ($supportUrl)
+{!! __('mail.support', ['site' => $site]) !!}
+
+{!! $supportUrl !!}
+@endif
+@if ($cancelUrl)
+
+{!! __('mail.suspendeddebtor-cancel') !!}
+
+{!! $cancelUrl !!}
+@endif
+
+-- 
+{!! __('mail.footer', ['site' => $site]) !!}
diff --git a/src/tests/MailInterceptTrait.php b/src/tests/MailInterceptTrait.php
new file mode 100644
--- /dev/null
+++ b/src/tests/MailInterceptTrait.php
@@ -0,0 +1,79 @@
+<?php
+
+namespace Tests;
+
+use Illuminate\Mail\Mailable;
+use Illuminate\Support\Facades\Mail;
+use KirschbaumDevelopment\MailIntercept\WithMailInterceptor;
+
+trait MailInterceptTrait
+{
+    use WithMailInterceptor;
+
+    /**
+     * Extract content of a email message.
+     *
+     * @param \Illuminate\Mail\Mailable $mail Mailable object
+     *
+     * @return array Parsed message data:
+     *               - 'plain': Plain text body
+     *               - 'html: HTML body
+     *               - 'message': Swift_Message object
+     */
+    protected function fakeMail(Mailable $mail): array
+    {
+        $this->interceptMail();
+
+        Mail::send($mail);
+
+        $message = $this->interceptedMail()->first();
+
+        // SwiftMailer does not have methods to get the bodies, we'll parse the message
+        list($plain, $html) = $this->extractMailBody($message->toString());
+
+        return [
+            'plain' => $plain,
+            'html' => $html,
+            'message' => $message,
+        ];
+    }
+
+    /**
+     * Simple message parser to extract plain and html body
+     *
+     * @param string $message Email message as string
+     *
+     * @return array Plain text and HTML body
+     */
+    protected function extractMailBody(string $message): array
+    {
+        // Note that we're not supporting every message format, we only
+        // support what Laravel/SwiftMailer produces
+        // TODO: It may stop working if we start using attachments
+        $plain = '';
+        $html = '';
+
+        if (preg_match('/[\s\t]boundary="([^"]+)"/', $message, $matches)) {
+            // multipart message assume plain and html parts
+            $split = preg_split('/--' . preg_quote($matches[1]) . '/', $message);
+
+            list($plain_head, $plain) = explode("\r\n\r\n", $split[1], 2);
+            list($html_head, $html) = explode("\r\n\r\n", $split[2], 2);
+
+            if (strpos($plain_head, 'Content-Transfer-Encoding: quoted-printable') !== false) {
+                $plain = quoted_printable_decode($plain);
+            }
+
+            if (strpos($html_head, 'Content-Transfer-Encoding: quoted-printable') !== false) {
+                $html = quoted_printable_decode($html);
+            }
+        } else {
+            list($header, $html) = explode("\r\n\r\n", $message, 2);
+            if (strpos($header, 'Content-Transfer-Encoding: quoted-printable') !== false) {
+                $html = quoted_printable_decode($html);
+            }
+        }
+
+        return [$plain, $html];
+    }
+}
diff --git a/src/tests/Unit/Mail/NegativeBalanceTest.php b/src/tests/Unit/Mail/NegativeBalanceTest.php
--- a/src/tests/Unit/Mail/NegativeBalanceTest.php
+++ b/src/tests/Unit/Mail/NegativeBalanceTest.php
@@ -4,16 +4,17 @@
 
 use App\Mail\NegativeBalance;
 use App\User;
+use Tests\MailInterceptTrait;
 use Tests\TestCase;
 
 class NegativeBalanceTest extends TestCase
 {
+    use MailInterceptTrait;
+
     /**
      * Test email content
-     *
-     * @return void
      */
-    public function testBuild()
+    public function testBuild(): void
     {
         $user = new User();
 
@@ -21,17 +22,19 @@
                 'app.support_url' => 'https://kolab.org/support',
         ]);
 
-        $mail = new NegativeBalance($user);
-        $html = $mail->build()->render();
+        $mail = $this->fakeMail(new NegativeBalance($user));
+
+        $html = $mail['html'];
+        $plain = $mail['plain'];
 
         $walletUrl = \App\Utils::serviceUrl('/wallet');
         $walletLink = sprintf('<a href="%s">%s</a>', $walletUrl, $walletUrl);
         $supportUrl = \config('app.support_url');
         $supportLink = sprintf('<a href="%s">%s</a>', $supportUrl, $supportUrl);
-
         $appName = \config('app.name');
 
-        $this->assertSame("$appName Payment Reminder", $mail->subject);
+        $this->assertMailSubject("$appName Payment Reminder", $mail['message']);
+
         $this->assertStringStartsWith('<!DOCTYPE html>', $html);
         $this->assertTrue(strpos($html, $user->name(true)) > 0);
         $this->assertTrue(strpos($html, $walletLink) > 0);
@@ -39,5 +42,12 @@
         $this->assertTrue(strpos($html, "behind on paying for your $appName account") > 0);
         $this->assertTrue(strpos($html, "$appName Support") > 0);
         $this->assertTrue(strpos($html, "$appName Team") > 0);
+
+        $this->assertStringStartsWith('Dear ' . $user->name(true), $plain);
+        $this->assertTrue(strpos($plain, $walletUrl) > 0);
+        $this->assertTrue(strpos($plain, $supportUrl) > 0);
+        $this->assertTrue(strpos($plain, "behind on paying for your $appName account") > 0);
+        $this->assertTrue(strpos($plain, "$appName Support") > 0);
+        $this->assertTrue(strpos($plain, "$appName Team") > 0);
     }
 }
diff --git a/src/tests/Unit/Mail/PasswordResetTest.php b/src/tests/Unit/Mail/PasswordResetTest.php
--- a/src/tests/Unit/Mail/PasswordResetTest.php
+++ b/src/tests/Unit/Mail/PasswordResetTest.php
@@ -6,16 +6,17 @@
 use App\User;
 use App\Utils;
 use App\VerificationCode;
+use Tests\MailInterceptTrait;
 use Tests\TestCase;
 
 class PasswordResetTest extends TestCase
 {
+    use MailInterceptTrait;
+
     /**
      * Test email content
-     *
-     * @return void
      */
-    public function testPasswordResetBuild()
+    public function testBuild(): void
     {
         $code = new VerificationCode([
                 'user_id' => 123456789,
@@ -24,20 +25,26 @@
                 'short_code' => 'short-code',
         ]);
 
-        // @phpstan-ignore-next-line
         $code->user = new User([
                 'name' => 'User Name',
         ]);
 
-        $mail = new PasswordReset($code);
-        $html = $mail->build()->render();
+        $mail = $this->fakeMail(new PasswordReset($code));
+
+        $html = $mail['html'];
+        $plain = $mail['plain'];
 
         $url = Utils::serviceUrl('/login/reset/' . $code->short_code . '-' . $code->code);
         $link = "<a href=\"$url\">$url</a>";
+        $appName = \config('app.name');
+
+        $this->assertMailSubject("$appName Password Reset", $mail['message']);
 
-        $this->assertSame(\config('app.name') . ' Password Reset', $mail->subject);
         $this->assertStringStartsWith('<!DOCTYPE html>', $html);
         $this->assertTrue(strpos($html, $link) > 0);
         $this->assertTrue(strpos($html, $code->user->name(true)) > 0);
+
+        $this->assertStringStartsWith("Dear " . $code->user->name(true), $plain);
+        $this->assertTrue(strpos($plain, $link) > 0);
     }
 }
diff --git a/src/tests/Unit/Mail/PaymentFailureTest.php b/src/tests/Unit/Mail/PaymentFailureTest.php
--- a/src/tests/Unit/Mail/PaymentFailureTest.php
+++ b/src/tests/Unit/Mail/PaymentFailureTest.php
@@ -5,26 +5,28 @@
 use App\Mail\PaymentFailure;
 use App\Payment;
 use App\User;
+use Tests\MailInterceptTrait;
 use Tests\TestCase;
 
 class PaymentFailureTest extends TestCase
 {
+    use MailInterceptTrait;
+
     /**
      * Test email content
-     *
-     * @return void
      */
-    public function testBuild()
+    public function testBuild(): void
     {
-        // @phpstan-ignore-next-line
         $user = new User();
         $payment = new Payment();
         $payment->amount = 123;
 
         \config(['app.support_url' => 'https://kolab.org/support']);
 
-        $mail = new PaymentFailure($payment, $user);
-        $html = $mail->build()->render();
+        $mail = $this->fakeMail(new PaymentFailure($payment, $user));
+
+        $html = $mail['html'];
+        $plain = $mail['plain'];
 
         $walletUrl = \App\Utils::serviceUrl('/wallet');
         $walletLink = sprintf('<a href="%s">%s</a>', $walletUrl, $walletUrl);
@@ -32,7 +34,8 @@
         $supportLink = sprintf('<a href="%s">%s</a>', $supportUrl, $supportUrl);
         $appName = \config('app.name');
 
-        $this->assertSame("$appName Payment Failed", $mail->subject);
+        $this->assertMailSubject("$appName Payment Failed", $mail['message']);
+
         $this->assertStringStartsWith('<!DOCTYPE html>', $html);
         $this->assertTrue(strpos($html, $user->name(true)) > 0);
         $this->assertTrue(strpos($html, $walletLink) > 0);
@@ -40,5 +43,12 @@
         $this->assertTrue(strpos($html, "$appName Support") > 0);
         $this->assertTrue(strpos($html, "Something went wrong with auto-payment for your $appName account") > 0);
         $this->assertTrue(strpos($html, "$appName Team") > 0);
+
+        $this->assertStringStartsWith('Dear ' . $user->name(true), $plain);
+        $this->assertTrue(strpos($plain, $walletUrl) > 0);
+        $this->assertTrue(strpos($plain, $supportUrl) > 0);
+        $this->assertTrue(strpos($plain, "$appName Support") > 0);
+        $this->assertTrue(strpos($plain, "Something went wrong with auto-payment for your $appName account") > 0);
+        $this->assertTrue(strpos($plain, "$appName Team") > 0);
     }
 }
diff --git a/src/tests/Unit/Mail/PaymentMandateDisabledTest.php b/src/tests/Unit/Mail/PaymentMandateDisabledTest.php
--- a/src/tests/Unit/Mail/PaymentMandateDisabledTest.php
+++ b/src/tests/Unit/Mail/PaymentMandateDisabledTest.php
@@ -5,25 +5,27 @@
 use App\Mail\PaymentMandateDisabled;
 use App\Wallet;
 use App\User;
+use Tests\MailInterceptTrait;
 use Tests\TestCase;
 
 class PaymentMandateDisabledTest extends TestCase
 {
+    use MailInterceptTrait;
+
     /**
      * Test email content
-     *
-     * @return void
      */
-    public function testBuild()
+    public function testBuild(): void
     {
-        // @phpstan-ignore-next-line
         $user = new User();
         $wallet = new Wallet();
 
         \config(['app.support_url' => 'https://kolab.org/support']);
 
-        $mail = new PaymentMandateDisabled($wallet, $user);
-        $html = $mail->build()->render();
+        $mail = $this->fakeMail(new PaymentMandateDisabled($wallet, $user));
+
+        $html = $mail['html'];
+        $plain = $mail['plain'];
 
         $walletUrl = \App\Utils::serviceUrl('/wallet');
         $walletLink = sprintf('<a href="%s">%s</a>', $walletUrl, $walletUrl);
@@ -31,7 +33,8 @@
         $supportLink = sprintf('<a href="%s">%s</a>', $supportUrl, $supportUrl);
         $appName = \config('app.name');
 
-        $this->assertSame("$appName Auto-payment Problem", $mail->subject);
+        $this->assertMailSubject("$appName Auto-payment Problem", $mail['message']);
+
         $this->assertStringStartsWith('<!DOCTYPE html>', $html);
         $this->assertTrue(strpos($html, $user->name(true)) > 0);
         $this->assertTrue(strpos($html, $walletLink) > 0);
@@ -39,5 +42,12 @@
         $this->assertTrue(strpos($html, "$appName Support") > 0);
         $this->assertTrue(strpos($html, "Your $appName account balance") > 0);
         $this->assertTrue(strpos($html, "$appName Team") > 0);
+
+        $this->assertStringStartsWith('Dear ' . $user->name(true), $plain);
+        $this->assertTrue(strpos($plain, $walletUrl) > 0);
+        $this->assertTrue(strpos($plain, $supportUrl) > 0);
+        $this->assertTrue(strpos($plain, "$appName Support") > 0);
+        $this->assertTrue(strpos($plain, "Your $appName account balance") > 0);
+        $this->assertTrue(strpos($plain, "$appName Team") > 0);
     }
 }
diff --git a/src/tests/Unit/Mail/PaymentSuccessTest.php b/src/tests/Unit/Mail/PaymentSuccessTest.php
--- a/src/tests/Unit/Mail/PaymentSuccessTest.php
+++ b/src/tests/Unit/Mail/PaymentSuccessTest.php
@@ -5,26 +5,28 @@
 use App\Mail\PaymentSuccess;
 use App\Payment;
 use App\User;
+use Tests\MailInterceptTrait;
 use Tests\TestCase;
 
 class PaymentSuccessTest extends TestCase
 {
+    use MailInterceptTrait;
+
     /**
      * Test email content
-     *
-     * @return void
      */
-    public function testBuild()
+    public function testBuild(): void
     {
-        // @phpstan-ignore-next-line
         $user = new User();
         $payment = new Payment();
         $payment->amount = 123;
 
         \config(['app.support_url' => 'https://kolab.org/support']);
 
-        $mail = new PaymentSuccess($payment, $user);
-        $html = $mail->build()->render();
+        $mail = $this->fakeMail(new PaymentSuccess($payment, $user));
+
+        $html = $mail['html'];
+        $plain = $mail['plain'];
 
         $walletUrl = \App\Utils::serviceUrl('/wallet');
         $walletLink = sprintf('<a href="%s">%s</a>', $walletUrl, $walletUrl);
@@ -32,7 +34,8 @@
         $supportLink = sprintf('<a href="%s">%s</a>', $supportUrl, $supportUrl);
         $appName = \config('app.name');
 
-        $this->assertSame("$appName Payment Succeeded", $mail->subject);
+        $this->assertMailSubject("$appName Payment Succeeded", $mail['message']);
+
         $this->assertStringStartsWith('<!DOCTYPE html>', $html);
         $this->assertTrue(strpos($html, $user->name(true)) > 0);
         $this->assertTrue(strpos($html, $walletLink) > 0);
@@ -40,5 +43,12 @@
         $this->assertTrue(strpos($html, "$appName Support") > 0);
         $this->assertTrue(strpos($html, "The auto-payment for your $appName account") > 0);
         $this->assertTrue(strpos($html, "$appName Team") > 0);
+
+        $this->assertStringStartsWith('Dear ' . $user->name(true), $plain);
+        $this->assertTrue(strpos($plain, $walletUrl) > 0);
+        $this->assertTrue(strpos($plain, $supportUrl) > 0);
+        $this->assertTrue(strpos($plain, "$appName Support") > 0);
+        $this->assertTrue(strpos($plain, "The auto-payment for your $appName account") > 0);
+        $this->assertTrue(strpos($plain, "$appName Team") > 0);
     }
 }
diff --git a/src/tests/Unit/Mail/SignupVerificationTest.php b/src/tests/Unit/Mail/SignupVerificationTest.php
--- a/src/tests/Unit/Mail/SignupVerificationTest.php
+++ b/src/tests/Unit/Mail/SignupVerificationTest.php
@@ -5,16 +5,17 @@
 use App\Mail\SignupVerification;
 use App\SignupCode;
 use App\Utils;
+use Tests\MailInterceptTrait;
 use Tests\TestCase;
 
 class SignupVerificationTest extends TestCase
 {
+    use MailInterceptTrait;
+
     /**
      * Test email content
-     *
-     * @return void
      */
-    public function testSignupVerificationBuild()
+    public function testBuild(): void
     {
         $code = new SignupCode([
                 'code' => 'code',
@@ -26,15 +27,22 @@
                 ],
         ]);
 
-        $mail = new SignupVerification($code);
-        $html = $mail->build()->render();
+        $mail = $this->fakeMail(new SignupVerification($code));
+
+        $html = $mail['html'];
+        $plain = $mail['plain'];
 
         $url = Utils::serviceUrl('/signup/' . $code->short_code . '-' . $code->code);
         $link = "<a href=\"$url\">$url</a>";
+        $appName = \config('app.name');
+
+        $this->assertMailSubject("$appName Registration", $mail['message']);
 
-        $this->assertSame(\config('app.name') . ' Registration', $mail->subject);
         $this->assertStringStartsWith('<!DOCTYPE html>', $html);
         $this->assertTrue(strpos($html, $link) > 0);
         $this->assertTrue(strpos($html, 'First Last') > 0);
+
+        $this->assertStringStartsWith('Dear First Last', $plain);
+        $this->assertTrue(strpos($plain, $url) > 0);
     }
 }
diff --git a/src/tests/Unit/Mail/SuspendedDebtorTest.php b/src/tests/Unit/Mail/SuspendedDebtorTest.php
--- a/src/tests/Unit/Mail/SuspendedDebtorTest.php
+++ b/src/tests/Unit/Mail/SuspendedDebtorTest.php
@@ -4,16 +4,17 @@
 
 use App\Mail\SuspendedDebtor;
 use App\User;
+use Tests\MailInterceptTrait;
 use Tests\TestCase;
 
 class SuspendedDebtorTest extends TestCase
 {
+    use MailInterceptTrait;
+
     /**
      * Test email content
-     *
-     * @return void
      */
-    public function testBuild()
+    public function testBuild(): void
     {
         $user = new User();
 
@@ -23,8 +24,10 @@
                 'app.kb.account_delete' => 'https://kb.kolab.org/account-delete',
         ]);
 
-        $mail = new SuspendedDebtor($user);
-        $html = $mail->build()->render();
+        $mail = $this->fakeMail(new SuspendedDebtor($user));
+
+        $html = $mail['html'];
+        $plain = $mail['plain'];
 
         $walletUrl = \App\Utils::serviceUrl('/wallet');
         $walletLink = sprintf('<a href="%s">%s</a>', $walletUrl, $walletUrl);
@@ -34,10 +37,10 @@
         $deleteLink = sprintf('<a href="%s">%s</a>', $deleteUrl, $deleteUrl);
         $moreUrl = \config('app.kb.account_suspended');
         $moreLink = sprintf('<a href="%s">here</a>', $moreUrl);
-
         $appName = \config('app.name');
 
-        $this->assertSame("$appName Account Suspended", $mail->subject);
+        $this->assertMailSubject("$appName Account Suspended", $mail['message']);
+
         $this->assertStringStartsWith('<!DOCTYPE html>', $html);
         $this->assertTrue(strpos($html, $user->name(true)) > 0);
         $this->assertTrue(strpos($html, $walletLink) > 0);
@@ -48,5 +51,15 @@
         $this->assertTrue(strpos($html, "See $moreLink for more information") > 0);
         $this->assertTrue(strpos($html, "$appName Support") > 0);
         $this->assertTrue(strpos($html, "$appName Team") > 0);
+
+        $this->assertStringStartsWith('Dear ' . $user->name(true), $plain);
+        $this->assertTrue(strpos($plain, $walletUrl) > 0);
+        $this->assertTrue(strpos($plain, $supportUrl) > 0);
+        $this->assertTrue(strpos($plain, $deleteUrl) > 0);
+        $this->assertTrue(strpos($plain, "You have been behind on paying for your $appName account") > 0);
+        $this->assertTrue(strpos($plain, "over 14 days") > 0);
+        $this->assertTrue(strpos($plain, "See $moreUrl for more information") > 0);
+        $this->assertTrue(strpos($plain, "$appName Support") > 0);
+        $this->assertTrue(strpos($plain, "$appName Team") > 0);
     }
 }