Your reference to Microsoft's tips are pretty much out of date. I've been running in circles attempting to get a delivery issue resolved with them and the majority of the addresses are no longer valid on their site.
Something I've recently run into, and many may be getting smacked for this is NDR and reverse NDR spam. I've been nailed by this recently and as a result, showed up on a blacklist.
I'm still pouring through the rules in Exim to figure out a way to minimize this. You can't really prevent it, short of turning off NDR, but then you'd be in running a mail server that doesn't conform to current mail standards. **sigh** I hate spammers.
|