[exim] Problems with user and/or mailaddresses including a "…

Exim does not accept mail addresses with a dash in the local part.
"Unknown user" is written into the logfile.
Dots (.) and underscores are allowed.

example: tom-Hanks@??? would not work, but tom_Hanks@??? or
tom.Hanks@??? works fine...

How to fix this problem?


Thanks a lot!!