mail aliases, mailinglist and netscape mail

Hello,

I have couple of mail aliases for my base e-mail
address(linux@esaravana.com). Eg, adrenaline@esaravana.com for my rock
climbing group. I use appropriate alias to subscribe to different groups
and receive mails. The problem comes when I post messages to the group.
The mail goes back as my base e-mail address(linux@esaravna.com), rather
than as my aliased e-mail address(adrenaline@esaravana.com) and gets
rejected.

Is there anyway I can add mail aliases to Netscape mail client and
choose appropriately as I send mails. Or should I do anything on my mail
server.

I am running RedHat 7.1 with Sendmail as my smtp server.

Sundar