[basic] How to run as more than one user conveintly

[reader@newsguy.com]

I'm supposed to know this I'm sure as a user of quite a few years
now. (quassia 16) But I'm just getting a very blank empty skull trying
to think how this is done nicely.

My regular email reader@newsguy.com has become so horribly inundated
with spam after some 10 yrs of open internet exposure that all my
filtering including procmail prefilters with SpamAssassin then
bogofilter followup, on my end and even some filters on newsguys
server end cannot keep up with this mess.  

As a non-business single user I get over 150 spams per day....

But cutting to the chase since I'm not posting for solutions to that..

I've opened a new email account that is blessedly low on spam starting
out but want to know how to run both accounts from one gnus with some
automation. I need this low-spam account to deal with a mission I have
at hand where I don't want to possibly miss something important or
spend time checking spam traps etc for something that should be handy.

Using current ntemacs but cygwin fetchmail/procmail.

I'm currently mobile and using winxp (against my will..).  I have the
basic setup in place using smtp send and fetchmail incoming but how to
manage both accounts so that the right stuff gets set automatically
for either user?  Is it normally done with `group params'?  If so can
I find examples somewhere?

In my case both users are with newsguy and share a password so it
should be somewhat simpler  I guess.