diff --git a/src/app/Http/Controllers/API/SignupController.php b/src/app/Http/Controllers/API/SignupController.php
--- a/src/app/Http/Controllers/API/SignupController.php
+++ b/src/app/Http/Controllers/API/SignupController.php
@@ -188,7 +188,7 @@
         }
 
         // Validate the verification code
-        $code = SignupCode::find($request->code);
+        $code = SignupCode::withEnvTenantContext()->find($request->code);
 
         if (
             empty($code)
diff --git a/src/app/Jobs/SignupVerificationEmail.php b/src/app/Jobs/SignupVerificationEmail.php
--- a/src/app/Jobs/SignupVerificationEmail.php
+++ b/src/app/Jobs/SignupVerificationEmail.php
@@ -51,7 +51,7 @@
     {
         \App\Mail\Helper::sendMail(
             new SignupVerification($this->code),
-            null,
+            $this->code->tenant_id,
             ['to' => $this->code->email]
         );
     }
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
@@ -3,6 +3,7 @@
 namespace App\Mail;
 
 use App\SignupCode;
+use App\Tenant;
 use App\Utils;
 use Illuminate\Support\Str;
 
@@ -31,8 +32,10 @@
      */
     public function build()
     {
+        $appName = Tenant::getConfig($this->code->tenant_id, 'app.name');
         $href = Utils::serviceUrl(
-            sprintf('/signup/%s-%s', $this->code->short_code, $this->code->code)
+            sprintf('/signup/%s-%s', $this->code->short_code, $this->code->code),
+            $this->code->tenant_id
         );
 
         $username = $this->code->first_name ?? '';
@@ -42,7 +45,7 @@
         $username = trim($username);
 
         $vars = [
-            'site' => \config('app.name'),
+            'site' => $appName,
             'name' => $username ?: 'User',
         ];
 
diff --git a/src/app/SignupCode.php b/src/app/SignupCode.php
--- a/src/app/SignupCode.php
+++ b/src/app/SignupCode.php
@@ -2,6 +2,7 @@
 
 namespace App;
 
+use App\Traits\BelongsToTenantTrait;
 use App\Traits\BelongsToUserTrait;
 use Carbon\Carbon;
 use Illuminate\Database\Eloquent\Model;
@@ -24,12 +25,14 @@
  * @property string         $short_code  Short validation code
  * @property \Carbon\Carbon $updated_at  The update timestamp
  * @property string         $submit_ip_address IP address the final signup submit request came from
+ * @property ?int           $tenant_id   Tenant identifier
  * @property string         $verify_ip_address IP address the code verify request came from
  * @property ?string        $voucher     Voucher discount code
  */
 class SignupCode extends Model
 {
     use SoftDeletes;
+    use BelongsToTenantTrait;
     use BelongsToUserTrait;
 
     public const SHORTCODE_LENGTH  = 5;
diff --git a/src/database/migrations/2024_06_13_100000_signup_codes_tenant_id.php b/src/database/migrations/2024_06_13_100000_signup_codes_tenant_id.php
new file mode 100644
--- /dev/null
+++ b/src/database/migrations/2024_06_13_100000_signup_codes_tenant_id.php
@@ -0,0 +1,43 @@
+<?php
+
+use Illuminate\Support\Facades\Schema;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Database\Migrations\Migration;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     *
+     * @return void
+     */
+    public function up()
+    {
+        Schema::table(
+            'signup_codes',
+            function (Blueprint $table) {
+                $table->bigInteger('tenant_id')->unsigned()->nullable();
+                $table->foreign('tenant_id')->references('id')->on('tenants')->onDelete('set null');
+            }
+        );
+
+        // We could set tenant_id for old records if there's only one tenant in the DB,
+        // but I think nothing will happen if we don't do this.
+        // Leave it to the deployment-specific migrations.
+    }
+
+    /**
+     * Reverse the migrations.
+     *
+     * @return void
+     */
+    public function down()
+    {
+        Schema::table(
+            'signup_codes',
+            function (Blueprint $table) {
+                $table->dropColumn('tenant_id');
+            }
+        );
+    }
+};
diff --git a/src/tests/Feature/Jobs/SignupVerificationEmailTest.php b/src/tests/Feature/Jobs/SignupVerificationEmailTest.php
--- a/src/tests/Feature/Jobs/SignupVerificationEmailTest.php
+++ b/src/tests/Feature/Jobs/SignupVerificationEmailTest.php
@@ -5,13 +5,12 @@
 use App\Jobs\SignupVerificationEmail;
 use App\Mail\SignupVerification;
 use App\SignupCode;
+use App\Tenant;
 use Illuminate\Support\Facades\Mail;
 use Tests\TestCase;
 
 class SignupVerificationEmailTest extends TestCase
 {
-    private $code;
-
     /**
      * {@inheritDoc}
      *
@@ -21,11 +20,7 @@
     {
         parent::setUp();
 
-        $this->code = SignupCode::create([
-                'email' => 'SignupVerificationEmailTest1@' . \config('app.domain'),
-                'first_name' => "Test",
-                'last_name' => "Job"
-        ]);
+        SignupCode::where('email', 'SignupVerificationEmailTest1@' . \config('app.domain'))->delete();
     }
 
     /**
@@ -35,7 +30,9 @@
      */
     public function tearDown(): void
     {
-        $this->code->delete();
+        SignupCode::where('email', 'SignupVerificationEmailTest1@' . \config('app.domain'))->delete();
+
+        parent::tearDown();
     }
 
     /**
@@ -45,20 +42,31 @@
      */
     public function testSignupVerificationEmailHandle()
     {
+        $tenant = Tenant::orderBy('id', 'desc')->first();
+        $tenant->setSetting('mail.sender.address', 'sender@tenant');
+        $tenant->setSetting('mail.sender.name', 'Tenant');
+
+        $code = new SignupCode();
+        $code->email = 'SignupVerificationEmailTest1@' . \config('app.domain');
+        $code->first_name = 'Test';
+        $code->last_name = 'Job';
+        $code->tenant_id = $tenant->id;
+        $code->save();
+
         Mail::fake();
 
         // Assert that no jobs were pushed...
         Mail::assertNothingSent();
 
-        $job = new SignupVerificationEmail($this->code);
+        $job = new SignupVerificationEmail($code);
         $job->handle();
 
         // Assert the email sending job was pushed once
         Mail::assertSent(SignupVerification::class, 1);
 
         // Assert the mail was sent to the code's email
-        Mail::assertSent(SignupVerification::class, function ($mail) {
-            return $mail->hasTo($this->code->email);
+        Mail::assertSent(SignupVerification::class, function ($mail) use ($code) {
+            return $mail->hasTo($code->email) && $mail->hasFrom('sender@tenant', 'Tenant');
         });
     }
 }