Hi Dov,
“2) A large file (>25MB) sent from outside did not come through and the sender did not receive a message delivery error - it just disappeared into the ether”
I’d like to confirm if when all the external users send emails with attachments(>25 MB), the issue occurs.
“3) A less large file (15MB) came through into everything (OWA, PC, and Mac).”
Do you mean no matter internal or external users send emails with attachments(<15MB), you are able to receive them on your Outlook 2011 client successfully?
Also, I’m waiting for your testing result of setting up the problematic account on other Outlook clients if possible.
By the way, the issue that customers have problem when sending emails on Outlook 2011 has been restored, so you can check if the issue on your side persists. If yes, this issue is different from the one mentioned by AppRiver, so please confirm the information above for further troubleshooting.
Thanks for working closely with us.
Best Regards,
Vivian Wang