Errors occurred while processing the attached Email

Hi Commit,

I am having some ERR emails with this information:
*** Errors occurred while processing the attached Email.
You should process this Email manually.
Reason: Error occurred while trying to find the sender Email address in CommitCRM database.
You should process this Email manually.

I have checked that
The e-mail address does exists - and only once.

Bonusinfo, recently I have upgraded CommitCRM to v.6

What can you suggest.

It should work unless the email is listed more than once, written incorrectly or that there is some file/s corruption. Please email us your RangerMSP log files using the Help > Technical Support menu in RangerMSP + Include in your email to us the EXACT email address you are referring to.

Thanks.

For your information,

I restartet the CommitServer and WebInterface - and now it is running again.