Hi, the last couple of days I have started seeing that one user incoming emails are getting stuck in the message trace as pending, and they are stuck there for hours.
The error message is always the same:
Reason: [{LED=432 4.3.2 STOREDRV.Deliver; mailbox database thread limit exceeded[retryinterval=00:03:09.0168217][retryqueue=False][retryscopetype=DatabasePriority]};{MSG=};{FQDN=DB7PR02MB4955.eurprd02.prod.outlook.com};{IP=};{LRT=11/14/2019 1:26:47 PM}]
I have gone through a lot of information regarding this but never found a solution to this problem, I haven´t even found the real reason for it to happen.
We are running the email service through office 365 cloud solution. No on-premise solution, we have also not migrated from an on-premise solution to office 365 cloud (which is something that was mentioned as an issue in this)
They users inbox is not even close to full (which is one thing that is mentioned as a issue in this)
I have increased this users incoming and outgoing email sizes to max (153600KB) (which is another thing mentioned), but it did not do anything, most of the email are around 100kb which is well below the limit (see attached images).
Have attached three images of one of the message traces.
If anyone has any additional information or perhaps even a solution on how to fix this that would be great.
