Does anyone know if incoming email will queue if postfix is stopped? I get the impression the mail is returned and hopefully re-sent. Is there a way to get the mail to queue until postfix is started again?
If the server is down, SMTP protocol should retransmit the mail. If the server is down for a long time (few hours), the SMTP server should emit a warning report to the sender and continue to retry. After few days of retries, the mail is dropped by the sender server and a error report is sent to the sender.