diff --git a/docker/kolab/utils/injectmimemessage.sh b/docker/kolab/utils/injectmimemessage.sh
new file mode 100755
index 00000000..27b244e0
--- /dev/null
+++ b/docker/kolab/utils/injectmimemessage.sh
@@ -0,0 +1,16 @@
+#!/bin/bash
+# Inject a mime message a users inbox.
+# * Write a mime message to $file
+# * Run 'injectmimemessage.sh $file' to inject the message into the TO users mailbox.
+# * Run 'injectmimemessage.sh $file $user@example.com' to inject the message into the $user@example.com's mailbox.
+
+if [ -z "$2" ]
+then
+    TO="-t" #use "To:" header instead
+else
+    TO=$2
+fi
+
+# The message id must be unique, otherwise messages get deduplicated.
+RANDOMID=$(tr -dc A-Za-z0-9 </dev/urandom | head -c 13 ; echo '')
+sed "s/message-id:.*/Message-Id: <$RANDOMID@generated.local>/gI" "$1" | /usr/sbin/sendmail -i "$TO"