Issues with mutt
 

I've been figuring out mutt the last few days, but no one seems to be able to recieve my emails, and I cannot send my emails. I had initially sent a test email to my other email account (hotmail), which arrived. I then changed the name of my computer (it was still local.localhost or whatever the default is). My emails to my own email account in hotmail still work, but I cannot recieve emails, and no one else recieves emails which I send. Have I missed something? (and yes, I did change the host name to the new one)

I just now recieved an error email:

[-- Attachment #1 --]
[-- Type: text/plain, Encoding: 7bit, Size: 0.6K --]

The original message was received at Mon, 8 Sep 2003 19:31:11 -0400
from daniel@localhost

----- The following addresses had permanent fatal errors -----
(friend's email, deleted for privacy)@carolina.rr.com
(reason: 553 5.5.4 <daniel@localhost.localdomain>... Real domain name
+required for sender address)
(expanded from: (deleted)@carolina.rr.com)

----- Transcript of session follows -----
... while talking to [127.0.0.1]:
>>> MAIL From:<daniel@localhost.localdomain> SIZE=514


Alternatively: is this program just not up to date? I find the idea of a command line mailer to be exciting, having only recently switched from windows... but is it technologically sound?