You may receive this error in your email client settings at some point. In Outlook this is a bug and can usually be resolved by restarting your email client and making sure you have SMTP authentication enabled. This is not a server problem and is caused by a mis configured email client, ISP's blocking access to port 25 and using port 26 instead or a DNS problem with your ISP.
To confirm that the mail server is online and responding you can perform the following:
From the 'Start' button click 'Run'
Type in 'telnet yourdomain.com 25'
You should receive something to the effect of:
220-server.dnsprotect.com ESMTP Exim x.xx #1 day, xx Month 2004 time
220-We do not authorize the use of this system to transport unsolicited,
220 and/or bulk e-mail.
This confirms there are *no problems* with the SMTP server
To confirm the POP server is online and responding:
From the 'Start' button click 'Run'
Type in 'telnet yourdomain.com 110'
You should receive something to the effect of:
+OK POP3 [cppop x.x] at [xx.xx.xx.xx] (yourdomain.com)
This confirms the POP server is online and there are *no problems* with the POP server.
Link to Microsoft support: http://support.microsoft.com/default.aspx?scid=kb;en-us;q295164
What can I do to reduce the amount of spam email I get?
1. NEVER click on an "unsubscribe" link on spam. That only serves to confirm that someone
actually reads the spam they send you...and they will then sell your email address to other
spammers.
2. If your email address is on your website, you might want to change to using a form mailer, for contact. Spammers harvest email addresses using a spider program. The spider searches websites and gathers any email address it can find.
3. If you participate in newsgroups / usenet, do NOT use your email address in the reply to field of your newsreader. Again, spammers harvest these groups for valid email addresses.
Also:
How do spammers harvest email addresses
http://www.private.org.il/harvest.html
SPAM - Munging Your Email Address
http://members.aol.com/emailfaq/mungfaq.html
http://www.internet-tips.net/Email/SPAM_munging.htm
How To Deal With Spam
Korean Spam Filter
http://www.siue.edu/~jpogats/korea.html
SPAM Tips and help
http://spam.abuse.net/spam/userhelp/
SpamCop
SpamCop FAQ Parsing and reporting spam
http://spamcop.net/fom-serve/cache/16.html
A Quick Guide to E-Mail Headers
http://real.fissure.org/articles/headers.shtml
Reading Email Headers
http://www.stopspam.org/email/headers/headers.html
Dealing With Junk Email
http://www.jcrdesign.com/junkemaildeal.html
The SPAM-L FAQ
