I'm trying to configure sendmail via webmin but having issues.  I'm
hoping to  be able to send email where ever I may be with my laptop. 
When at home I use outlook mail client and set outgoing mail to
smtp.comcast.net as a setting to my domain (name@domain.com),  but
when I go elsewhere I can't send out email. I would like to program my
email so it relays through my dedicated server, which is currently
running sendmail.  Please provide detailed instructions so I can
follow.  Step by step should include icons and specifics involved. 
I'm not all the technical but am able to follow directions if the are
compete and descriptive. Do not assume anything as I am new to this
process.

ISPs are pretty monogamous about only their customers using their SMTP
servers. Some ISPs even refuse to allow you to send if the user
doesn't use *their* SMTP server.

Here's a site that can help you use sendmail with SMTP authentication:
http://www.megalinux.net/archives/000027.html
(Your default install may not have SASL support).