SymptomsSmarterMail is used as mail server in Plesk. Mailbox firstname.lastname@example.org is configured to forward mail to email@example.com, firstname.lastname@example.org has enabled autoresponder.
When mail is sent to email@example.com directly, autoresponder works correctly.
When mail is sent to firstname.lastname@example.org and redirected to email@example.com, autoresponder does not work.
The same configuration on Mailenable server does work correctly in both cases.
CauseThe reason of such behavior is that in SmarterMail Autoresponder works by event on SMTP service. But SmarterMail redirection does not use SMTP service when mail is redirected locally.
So Autoresponder simply does not run in this case.