In Exchange 2010 or another other version like 2013 or 2016, you probably came across the fact that when a user sets up there out of office, all looks fine. You receive the mailtip in outlook, you can check the event logs on the CAS server and it will show as successful however you don’t receive the OOF email.
This can be a number of things but in this example I would like to show you another possibility of why this would happen.
Recently, we had a user that setup OOF, however the mail was not sending. Looking at the CAS server, no errors were logged for that specific user.
The next step was to look at the Mailbox Server where the user’s mailbox was homed. Upon checking the eventlog, the error stood out like a sore thumb, not one you would have expected.
Event ID 3004 was logged on the Mailbox Server and its error listed as follows:
The Rules quota of mailbox User@domain.com has been reached and the automatic reply rules can’t be enabled or updated. Delete some existing rules or increase the user’s rule quota and try to set the automatic reply again. You can use the Set-Mailbox cmdlet to increase a user’s rules quota.
Now by default, the user has a rule quota of 64k. We just increased the rules quota to 256k and the user was able to set OOF again and users’ internally and externally were now getting the OOF message.
Hope it helps.