We have Office 365 Exchange Online Plan 1 and every week we get several false negatives passing directly to the Inbox, in addition to the numerous false positives. And if it needs explaining, the users get conditioned to "release from quarantine" because of all the false positives and then start releasing valid quarantined items too.
When I used to be on Postini it wasn't like this. I would have one false positive a month.
I've already enabled most of the advanced spam detection options and spoken with Microsoft tech support.
Now I'm ready to add an additional spam filtering service.
Do you have any recommendations on a 3rd party, hosted, spam filtering service that would go in front of the delivery to Microsoft's service?
Sender 3rd party spam filter Microsoft Office 365 spam filter delivery to end user
It's a shame that I can't trust...