Sendmail help sought

[Timothy Murphy]

I'm puzzled by MASQUERADE_AS and MASQUERADE_DOMAIN in sendmail.mc .

I'm using KMail (under Fedora-12) on my laptop to send and receive email.

I send my email through my ISP, as defined by
define(`SMART_HOST', `smtp.eircom.net')dnl
in /etc/sendmail.mc on the laptop.

I collect my email on my desktop from my ISP and other sources,
by running fetchmail as cron.d jobs.
I run dovecot IMAP on the desktop,
and read the email on my laptop as IMAP.

Should I set MASQUERADE_AS and/or MASQUERADE_DOMAIN 
on laptop and/or desktop?
Currently I have them both set on both machines to my ISP,
MASQUERADE_AS(`eircom.net')dnl
MASQUERADE_DOMAIN(eircom.net)dnl
but I'm not sure if this is necessary, or wise.

Any enlightenment gratefully received.

-- 
Timothy Murphy  
e-mail: gayleard /at/ eircom.net
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland