MDaemon has an option very similar to fetchmail's 'qvirtual' option
(for stripping prefixes off Delivered-To lines). It's in the
'DomainPOP Mail Collection' config box, tab 'Processing'. Bottom box
named 'Address Processing'. Tick first box ('Strip Text From Left')
and enter text to be stripped in the textbox.
Some of your customers may be interested in this. I now hacked my
forward-wrapper to fix up DTLINE without the prefix, because some of
our customers have severely broken mailers.
Greetz, Peter.