sendmail question

[Chris Hare]

This might not be the right forum, so I apologize up front.
 
I have a situation where my ISP requires outbound SMTP to be authenticated,
such as in a mail client.  I have an application I have built that sends
email to users when there is a severe weather event.  Some of those users
are at my ISP.  (If they are not, it isn't an issue.)  Is there anyway to
configure sendmail to do outbound authenticated SMTP to another mail server?

 
This issue is also important, because this ISP (comcast) only provides a
java/macromedia web mail client, which my PDA can't access.  I have
squirrelmail running now, which it can, but since I need authenticated
outbound SMTP, I can't send email. Not very useful.
 
Thanks
Chris