I'm having an issue with a client. They are using hosted exchange with Outlook 2013 and 2016.
Every day from 11:30am till noon their Outlook will not send emails. The progress bar just spins on "sending email", but there is no progress.
After Outlook is restarted, it will send perfectly for the rest of the day.
I have checked the following: any anti virus scans, any scheduled tasks such as backups ect. I have also ran a network connection ping to both the exchange server and Google (as a control subject). The connection is not lost when this happens.
The only common task I see running is the MS Office license validation service.
They are running in cached exchange mode. Any ideas?