shared mailbox - inbox partly in subfolder

[marek_siatkowski]

I have a shared Mailbox.

In this Mailbox some subfolders were automaticall created. The incoming Mail goes to three different folders by random, or at least I do not see why some mails are goint to Posteingang and some to Eingang. The Mails going to Ausgang seem to be all Mails which were send by some Flow for an other shared Mailbox.

Can someone Explain this or give some goog google search words? 

[#2]

check the messagetracking in exchange admin center to see what is happening with the mails.
or copy and paste the email headers into mxtoolbox header analyzer to see.
check for rules on the mailbox, can be done in outlook client or via powershell.
get-inboxrule -identity "mailboxname"
if there is no reason for these sub folders to exist delete them and send a test email to see if it lands in the inbox.

[#3]

Check the Mailbox Rules
https://learn.microsoft.com/en-us/powershell/module/exchange/get-inboxrule?view=exchange-ps
Get-InboxRule -Mailbox email address removed for privacy reasons

Regards
Andres