Long story short: Since we were missing a sent e-mail on the Exchange server, the blame on the current CRM 2016 (8.2.2) increased. Now our sysadmins are searching all different stuff, what the system not does... instead of upgrading their old exchange 2010.
Currently I am facing two issues:
1. The CRM receives emails from the Exchange (EWS) that are S / MIME encrypted. But as far as I understand, the CRM does not modify or change the emails. It just retrieves the existing ones from the exchange mailbox? If the CRM can not handle the S / MIME messages, that means I need to write a plugin on the email creation, to decrypt the incoming mails?
2. I was looking for the missing e-mail and the state in the CRM what "sent". Even the record had the message-id that (as I read) should be the ID coming from the Exchange. Is there any clear documentation or statement, that every email in the CRM with the state "sent" was really sent by the Exchange?
EDIT:
1. Our IT told me that every E-Mail with a attachment is a S/MIME. That was not truth. A test showed that normal e-mails got not changed by the CRM in any way. The only problem comes from e-mails that are received as S/MIME.