Dear Support,
We have 500 plus pro version Licenses of EM Client, recently we have migrated our On Premises Microsoft Exchange Server to Exchange 2019 and observe abnormal delay in receiving and sending emails through email client using EM Client with Exchange Web Services profile specially sent emails stuck in outbox for the long periods of time. On the other hand, users on Microsoft Outlook are not facing any delay and they are absolutely working fine.
Further we have already troubleshot all possible scenarios like upgraded EM Client on most updated version, create fresh profile after removing old, completely remove antivirus software and using direct LAN connection where no VPN involve but issue persists.