I have worked with TWO customers today with the same issue, and I saw it firsthand.  Both customers are on Yosemite.  One was using Outlook for MAC 2011 and one was using MACMail. 

Emails that are being sent from the Drafts folder re-appear in the Drafts folder after being sent.  The emails are sent and do appear in the Sent Items folder.  However, they also re-appear in the Drafts folder as if they haven't been sent.  I was connected to both customers' MAC's via Remote Support, and I even tried to delete the emails, but the emails re-appeared.  I closed MACMail and re-opened it and still the emails are in the Drafts folder.  My other client has also closed Outlook 2011 and re-opened it, only to see the emails still in the Drafts folder.  This is VERY confusing to both clients, and I am scratching my head on this as well.  Any thou

Hi,

In this forum we mainly provide suggestions about Outlook for Windows, as your question is about Outlook for Mac, I suggest you post the question in the Office for Mac forum to get more dedicated assistance:

http://answers.microsoft.com/en-us/mac

The reason why we recommend posting appropriately is you will get the most qualified pool of respondents, and other partners who read the forums regularly can either share their knowledge or learn from your interaction with us. Thank you for your understanding.

Regards,

Melon Chen
TechNet Community Su