Office 365 Outbox Woes

[Mr_Jiminy]

I'm experiencing an odd problem with emails sent from the Outlook client (in this case 2016) are sitting as pending delivery in my OWA Outbox folder. The Outlook client informs me the message has delivered, in fact a delivery report confirms delivery at the other end. It's OWA where I'm experiencing the issue.

 

I suspect I'm going to have to log a support case, but wanted to check prior to doing so.

[MatthewL]

Have you sent from OWA and are they ok? Also have you tried a fresh profile for Outlook also deleting local profile if you can on PC and recreating and trying it from a different PC as I had similar years ago with Exchange 2003.

[Mr_Jiminy]

It's certainly an odd one, the problem is happening on three clients, all of which are running Windows 10 (latest revision) with Office 2016 Pro Plus.

 

Mail only sticks in the OWA outbox when sending from the Outlook client, sending mail from the OWA client works absolutely fine.

 

My suspicions at the moment are either the new Windows 10 update, an Office 2016 update or a problem in the O365 tenant.