Incoming Username Split Recepie

Hi

Can someone provide me with the correct syntax for splitting off the pre
'@' bit of the senders address and putting the mail a file (not mh)
called this?

Additionally I would like to do the same with mail I send.

TIA

Regards,

Stephen.

-- 
Stephen Johnston                                Phone: +49 89 32006 443
UNIX Sysadmin                                   Fax:   +49 89 32006 380
SERCO GmbH at European Southern Observatory
Karl-Schwarzschild-Strasse 2                    
mailto:sjohnsto(_at_)eso(_dot_)org
D-85748 Garching bei Muenchen                   http://www.eso.org