Need help with sendmail to rid me of cc:mail!

Hi

OK I work for an internet fax provider and have used cc:mail for ages to do this using cc:mail postoffices - we dumped it for our normal emails ages ago but our customers hate change =(

I need to somehow translate/forward a certain pattern of email address to a particular postbox called 'faxgateway'.

e.g. to send a fax to fax number 123456789 the cc:mail email address would be URL

For our sendmail gateway it is URL and we currently forward all traffic going to fax.domain.com to the postbox 'faxgateway'.

Is there a way of sending all emails to
[whatever]_at_fax@domain.com in the same way?

Can virtualusertable work with part emails?

Or is there a clever filter to rewrite '_at_fax@domain.com' to be '@fax.domain.com'?

Or any other way of doing this so we can get rid of the aging pile of poop called cc:mail?

Thank you in anticipation!!

Ian