Last year we migrated our environment from Lotus Notes to Exchange 2010.
As such, we’re using Outlook 2011 on our Mac clients.
Some users accounts would just keep downloading.. after much head scratching & hair tearing we found the issue.
It appears that within the folders that were constantly trying to download contained e-mails with BinHex attachments, as per the linked document this would be the attachment format that a Mac Lotus client would in some situations send out.
- Login to OWA as the affected user.
- Search across the whole mailbox for .hqx
- Download all the attachments if wanted.
- Delete the offending e-mails.
- Log out of OWA.
- Open Outlook 2011 & sync.
Others have verified the issue with me. Strangely when using OWA, Outlook on a PC over MAPI, Outlook on a PC HTTP over RPC or Mail using EWS this problem does not exist.