No policy can override truth and facts.
I'm not going to comment other than say that this sub-thread probably needs to continue on:
alt.flames.anti-microsoft.linux.jihad
no. no jihad. No linux actually (i don't use linux).
That's fact. If someone want to use outlook then fine, but should not expect anyone else than microsoft to fix it's problems and speed.
It is nothing to do with dovecot.
All my experience with that shit now is remote.
I quite often handle complaints from users that
a) "my mail wasn't delivered to somebody."
After checking logs i found that recipent's server received mail with success. But mail disappeared then.
Sometimes reappeared after a week, sometimes many times, or never ;)
The reason was microsoft exchange on recipient side. Sometimes - badly configured antispam.
b) reverse - "i don't receive mail from someone".
Because someone's MS exchange server didn't even try to send it.
c) i'm getting some strange attachment that i cannot open. (winmail.dat)
my answer: Ask sender to send attachments according to standards