Exchange 2019 problem with sending mail - recently I have a problem with sending mail. When sending using MS Outlook, you are constantly prompted for the password (the password is saved in the settings and everything worked correctly before). When you try to send mail using OWA, the message is placed in draft. The problem started sporadically yesterday and permanently today. I recently installed Exchange CU11 and it started to occur more frequently after that. All services work and errors can be seen - where to look for the cause?
I found Warning: Inbound authentication failed with error LogonDenied for Receive connector Client Frontend CELLO2. The authentication mechanism is Ntlm. The source IP address of the client who tried to authenticate to Microsoft Exchange is [x.x.x.x]. ???Janusz