Hi Mohamed,
This is Neo Zhu from Office365 support. I’m glad to work with you on this case.
Based on your description, I understand your user encounter the problem about the mail delay sending problem. The users who are located in US & UK and use Mac entourage are facing this problem. The email messages are stucked in “Outbox” , then spend too much time on sending. Everything works fine in OWA.
I’d like to know which region you are using when register the Office365 tenant. Other question is how long it takes to send a mail in US & UK. I’m asking this because I think it could a connectivity problem between the user’s location and the mailbox server location ( It means post-443 connection) .
Additionally, I also would like to check your Outlook 2011 logs , you can enable them via www.officeformachelp.com/.../logging
By the way, if we use Outlook 2010/2013 , do you face the same problem?
Thanks,
Neo Zhu