Have you tried entering your username with no CAPITAL LETTERS?
Have you tried with it both followed and not followed by the part of
your email address starting with @?  Are you sure you use CAPITAL
and lowercase letters in the right places in your password?  Some,
but not all, email servers are set to be picky about such things.

Also, if you have set Windows Mail to remember your password
and only see this problem when it's using its remembered password
you may be running into a quirk in what it does when you click
Apply after applying the remember password checkmark.  It
forgets the password if you do this.  If you think this is the case,
click on Tools, then Accounts, then your email account, then
Properties, then Servers.  If there is no check mark in the box
before Remember password, click on this box.  Don't click on
Apply, as you normally would after a change.  Click at the end of
the password, then backspace over it, then enter the password
again, with any approvals needed.  Don't click on Apply.  Click
on OK, then Close.

Also, you might check on your settings for the outgoing mail server
since port 110 is seldom used for an outgoing email server.  It is
often used for the incoming email server, though.

Check with the company running that server for the correct
settings.  They don't seem to have put them on their web site,
if I was looking at the right web site.

Do you have antivirus software disabled?  See www.oehelp.com/OETips.aspx#3

steve

On the Servers tab check the box on the bottom for outgoing server:
"My server requires authentication".
Looks like you didn't do that.