Recently trying to setup a mail re-direct (or a cc) to an external e-mail address. It is important to first determine if you are running courier or dovecot because the syntax is different. Under dovecot, it should be in sieve syntax. Therefore, under ISPConfig3 -> Email -> Email Mailbox -> Custom Rules, enter: redirect "mail@example.com"; Ensure it is double straight quotes and semi-colon at the end. Wait until the update is done (usually a few minutes) via the cron jobs of ISPConfig3 updating the /var/vmail/domain/username/.sieve
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