Add mail server port.

nbspplenumbot.sh

 #!/bin/sh
-export MAIL_SERVER='mail.chaotikum.net';
+export MAIL_SERVER='mail.chaotikum.net:587';
 export MAIL_USER='noreply';
 export MAIL_PASSWORD='<MAIL_PASSWORD>';
 . /home/bots/scripts/nbspplenumbot/venv/bin/activate;