Update Check-SharedMailboxes.PS1

[gioxx]

I propose a change to filter out false positives related to shared mailboxes that do not actually log in, but third-party login attempts that are unsuccessful and therefore not subject to the mandatory license at all.

[12Knocksinna]

Do you see many false positives?

[gioxx]

Ciao @12Knocksinna.
On my corporate tenant, about 15 shared mailboxes out of 534 (just made PowerShell count). I am aware that this is a very low number, but I still have to take it into consideration. And in fact, by manually checking the access logs after receiving the results from your script, I noticed it. By modifying the script, I got the shared mailboxes that needed a dedicated license (and solved a couple of situations).

So again, thank you for your work 😃