We check our customer backups by monitoring a mailbox that receives mails from their backup software. But a while ago PRTG started throwing errors saying "Could not access the mailbox (PE: 124)".
We are thinking this is because of some limits set on Exchange Online. A Microsoft Engineer confirmed this to us. But now we need a solution for this problem.
We are currently doing 100 checks.
We tried spreading the checks by setting it to scan every 4 hours and creating schedules as following: schedule1 - Pause from Saturday 9:00 until Tuesday 9:00 schedule2 - Pause from Saturday 9:10 until Tuesday 9:10 schedule3 - Pause from Saturday 9:20 until Tuesday 9:20
There is one schedule for every 10 mails.
This does not seem to help though. Most checks started failing again.
Anyone that knows how to fix this?
I also should say that these checks sometime take around 400 seconds to complete. Which is way longer than it should.