Teams Voicemail E-Mail Header not RFC compliant

We are using Teams Voicemail. The Voicemail is send by Mail directly to exchange online mailboxes.

The Mail Header of this E-Mails are not RFC compliant. The Header-From ist not a valid Mailbox - it’s just the PSTN Number of the Caller.

This results in problems with other systems connected to exchange online, e.g. our archiving service rejects the archival.