fetchmail with multiple accounts

[Nano Nano <40208.nospam@comcast.net>]

I have seven different email accounts at Comcast.net, all used for 
various purposes.  At the comcast level I have mail forwarded / don't 
leave a copy for six of the emails to the "primary" email.  Then I use 
fetchmail to deliver the mail to my local user spool.

It's efficient and easy (only poll one pop account), get all mail in one 
fell swoop, but it's impossible to tell which of the seven emails spam 
with forged headers was orignally delivered to -- comcast doesn't add 
any headers when it does its internal forwarding.

I'm thinking what I need to do is stop the internal forwarding at 
comcast and have fetchmail poll each pop account seperately.  Can I 
configure fetchmail or exim to add a header so I can still deliver all 
the mail to the same spool?  If not, should I create bogus user accounts 
with shell=/bin/false and just give RW permissions to my account on 
their spools?

Thanks