I'm having repeated trouble with Microsoft owned domains. They have a
proprietary SmartScreen system which they do not seem to be able to
control (according to their own support teams). It means that I
frequently find all mail to @hotmail @outlook etc is returned with a
"550 5.5.0 Requested action not taken: mailbox unavailable." message.
I use exim to send bulk mail (e.g.newsletters from my CRM) and also
transactional emails - I run several petition tools which send a "Thanks
for signing, please ask your friends to sign" sort of emails - these can
get quite popular and generate a lot of mail in a short period.
All mail is DKIM signed; SPF is in place; PTR records too. I believe my
server is set up properly.
The Solution I'm Asking About
I was wondering if it would help things if I rate limited the sending of
mail to Microsoft. e.g. mail to these domains gets put in queue and that
queue gets processed at a certain rate.
How would I implement that? I'm using exim 4.89
Other advice?
If anyone has any other advice on the problem it would be gladly received.
