You’re not a newbie–you know you have all your email settings configured properly in your email client (Outlook, Thunderbird, etc). In fact, you can send and receive email just fine from one ISP. But when you connect your laptop at a different location which uses a different ISP, all of a sudden you can’t send outgoing email. You get an error message like this one:
Send Message Error in Thunderbird
The issue:
In an effort to stop spam, many ISPs (Comcast, Cox, many others) block all traffic to port 25 on anything except their own SMTP servers.
The fix:
Replace the default SMTP Port 25 with 587. RFC 2476 explains why this works for newer SMTP servers. (For sbcglobal.net, the fix is to change port to 26.)
Alternate fix:
You will have to use your ISP’s default SMTP servers. Here is a tentative list that has not been checked for accuracy:
- Earthlink: smtpauth.earthlink.net (To verify, visit http://www.earthlink.net)
- Comcast: smtp.comcast.net (To verify, visit http://www.comcast.com)
- Sympatico: smtp1.sympatico.ca or smtp8.sympatico.ca (To verify, visit http://www.sympatico.ca)
- AT&T: mailhost.att.net (To verify, visit http://www.att.net)
- Netzero: smtp.netzero.com (To verify, visit http://www.netzero.net)
- Charter Communications: smtp.charter.net (To verify, visit http://www.charter.com)
- MSN: smtp.email.msn.com (To verify, please check with your MSN provider)
- RCNL: smtp.rcn.com (To verify, visit http://www.rcn.com)
- BellSouth.net: mail.bellsouth.net (To verify, visit http://www.bellsouth.net)
- Cox.net: smtp.east.cox.net (CT, FL, GA, LA, NC, OH, RI, VA); smtp.central.cox.net (KS, NE, OK, UT, West TX); smtp.west.cox.net (AZ, CA, NV); smtp.cox-internet.com (for @cox-internet.com customers
in AR, ID, LA, MI, East TX, Tyler). Port 587 may also be required for SMTP. To verify, visit http://www.cox.net - Rogers: May require port 587 for smtp. To verify, visit http://www.rogers.com
- AOL: May require port 587 for smtp. To verify, visit http://www.aol.com.
