Getting user@domain.com in Linux

From testing sendmail (and I am a newbie at that), I am able to send e-mail and receive e-mail using user@host.domain.com format. I have Comcast residential so I had to change SMART_HOSTS to my ISP's SMTP server addy and that way my e-mail was not treated as spam (coming from a dynamic IP block). However....

'Enter a host name' is what Slackware asks me to name the computer so I give it a name ...say...papajohns. Is it possible, without paying a third party, to give yourself an e-mail like admin@domain.com as opposed to admin@papajohns.domain.com using Sendmail or another kind of Mail Server program?

Any input would be greatly appreciated.

(nevermind)

uhh...I did it...somehow...I think it depends on where you're sending it from...I had the same problem until I started sending from an external IP...like if I use the mail command right from the local terminal, it was always "server.domain.tld", but if I used Dovecot to connect to the server, like putting "domain.tld" in as the server to send mail to that would then be sent, I got the "domain.tld" to appear as the from. This only worked though, if you have sendmail configured right. Personally, I preffer Postfix...but thats just me. Postfix is easier to configure with Dovecot, and generally easier to troubleshoot. Use the mail switcher to switch to Postfix if you like.

Scott