Our application sends out a lot of email notifications! how can I send out email notification without causing long delays?
(its not a email newsletter, its account notifications)
Send plain-text notifications only, keep em short and sweet. (Think tweet)
Use QOS on router/firewall to lower the priority of the outbound email.
Send in batches, say, 50 every 10 minutes.
Once upon a long time ago I was given the task of streamlining the processing of sending mail to a quarter of a million subscribers. (I was the senior sysadmin at a little anti-virus company and this was the list that people subscribed to for notification when the regular "defs" (virus pattern definition) files were posted to our BBS (remember those?), FTP and web sites).
My first step was to normalize that addresses (down to just email@example.com) and then sort that through the command:
Of course I also scaled it out over a couple of machines, later.