We are running an Exchange 2007/2013 Hybrid and we have an issue with Outlook 2010 users still on Exchange 2007.
We see that at random all messages sent will stay in the Outbox and not move.
On checking the mail profile we notice that under the Email tab an extra entry has been added. If we remove it and re-open Outlook the mail starts to flow again.
Has anyone seen anything similar ? All our users are using cached mode.