Ian Evans: > Sorry if this is OT. My hosting service is migrating our VPS to new > hardware. I plan to shut down postfix (it's just me and the missus) and > create a snapshot prior to the shutdown. > > How long do servers try to resend email if your server is temporarily down? > The host has given themselves an 8 hour overnight window.
"It depends". There is a difference between wat rules say (in this case https://www.rfc-editor.org/rfc/rfc5321#section-4.5.4) and what real systems do. But the rules are still a good guide. Postfix retries for 5 days with intervals that slowly increase from 5 minutes to 4 hours. But with a queue of millions of files it may take an unreasonable amount of time to catch up. Other systems may give up after hours, to prevent the mail queue from becoming unreasonably large. Wietse
