MicrosoftMicrosoftWe are experiencing a strange behavior after installing Exchange 2019 CU 13 and the security update after that. There seems to be a bug.
Environment:
We are running Exchange Server 2019 (Hybrid environment). All mailboxes are in the cloud. The on-prem server is for management and SMTP service only.
Problem
Whenever the user receives a system generated "Mailbox is full" email from Exchange, our user (if they are out of the office and have OOF set up) sends the automated "Out-of-the-Office" reply to Exchange's Primary SMTP Email address, MicrosoftExchange329e71ec88ae4615bbc36ab6xxxxxx @blahblah dot com(changed for privacy but similar to that), which appears to be Exchange's Postmaster also. However, since this Exchange mailbox, MicrosoftExchange329e71ec88ae4615bbc36ab6xxxxxx, is the postmaster, which happens to be an email distribution group, the members of the Postmaster group gets tons of random emails.
Does anyone experience this? Postmaster used to not receive OOF emails. Is this a bug? Can we stop or prevent MicrosoftExchange329e71ec88ae4615bbc36ab6xxxxxx to email a copy, forward or receive OOF from users? We didn't experience this before and only after the Exchange CU.
Thanks,
