ID #218

Sending email takes a long time and then fails.

Applies to: Grid System

If, whenever you try to send email from a program on your computer like Outlook or Eudora, it takes a long time to authenticate and then fails, then the reason is most likely because your attempt to relay has been blocked by your Internet Service Provider (dialup modem, DSL, cable, broadband).

More and more ISPs (MSN, Earthlink, Verizon, NetZero, Mindspring, Flashnet, MediaOne, AT&T, AT&T Broadband (ATTBI), Bell Sympatico, etc) do not allow their customers to use outgoing mailservers (smtp servers) other than their own, and enforce that by blocking their customers from accessing any remote servers on smtp Port 25:

Hotmail spam filters block outgoing e-mail
MSN filter sparks subscriber ire
Verizon's Anti-competition Email Policy

The solution to this problem is to contact your ISP and ask them what Outgoing Mailserver they want you to put in your mail program settings.

Another possible cause is that you have a personal firewall running on your computer like Norton Anti-Virus, Black Ice Defender, or Zone Alarm that is not allowing this type of activity. The solution in that case is to either turn off that software, or configure it to allow you to relay mail.

Known ISPs who block remote Port 25/SMTP Access

Your ISP may be blocking your access even if they are not on the list below. Please contact your ISP and ask them for the Outgoing/SMTP server that they want you to use.

ISP Mandatory Outgoing Mail Server
AltaVista Free Access
AT&T WorldNet
Microsoft's MSN
Prodigy Internet
Verizon/GTE (Dial-Up)


Last update: 2010-10-03 16:30
Author: FAQ Admin
Revision: 1.2

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Comment of Anonymous:
I dial-up with a local (non-nationwide) ISP. They have also blocked port 25, and require that all SMTP packets go through The ISP is SnowCrest.
Added at: 2002-11-05 13:55

Comment of Anonymous:
Cox Communications also blocks port 25.
Added at: 2004-07-08 14:24

Comment of Anonymous:
optimum online is blocking 25 too
Added at: 2003-05-30 10:11

Comment of Anonymous:, a large discount dialup provider, is blocking access to port 25 on remote servers. I went to and checked with about five more low-cost dialup providers. All but one said they do the same. Joi at said they are not blocking. I signed up and "we'll see".
Added at: 2003-06-30 12:57

Comment of Anonymous:
Comcast's outgoing SMTP is:
and it requires NO authentication.
Added at: 2004-04-29 18:20

Comment of Anonymous:
A list of major ISP's and their outgoing SMTP email relays:

Actrix Networks - -
AT&T -
AT&T Business Internet -
AT&T Worldnet -
Bell Atlantic -
Blazenet -
BlueYonder -
BusinessServe -
BTClick -
BT Internet -
BT Openworld -
Cableinet - -
Claranet -
ClearNet -
Coastalnet -
Compuserve -
Concentric -
CWCom - -
Charter - Pipeline -
CalWeb -
Comcast - -
Crosslink - - -
Demon -
DirectConnect -
Earthlink -
Easynet -
Erols - - -
Freeserve -
Gateway -
Genie -
Globe - Net -
GTI - -
IC24 -
Iprolink -
Juno - no relay
Lineone -
LogonAmerica -
Lycos -
Madasafish -
MegaNet -
Mindspring -
Mistral - -
Netcom -
Netlink -
Netreach -
Netzero -
Nildram - -
NTLWorld -
OneTel -
OptimumOnline -
Orcon -
PacBell - -
Paradise - Net -
PeoplePC -
Pipeline -
Pipex -
Purplenet -
Prodigy -
PSINet -
PSINet -
Quadnet -
River City Internet -
Screaming.Net -
Spire -
Sprynet -
StarPower -
Supanet -
Telecom Xtra -
Telewest -
Tesconet -
Tiscali -
Totalise -
UKGateway - - -
V21 -
Valinet -
Verizon -
Virgin -
Vispa -
Voicenet -
Waitrose - -
Webcom -
Which Online -
Worldonline -
Yahoo -

Added at: 2004-10-18 20:04

Comment of Anonymous:
You can get around this by simply using Windows Pro SMTP server, and using a different port. Cox and others also block port 80 so you can't run a web server, unless you change the port to something like 8080. THen yuo ahve something like
youipaddress:8080. If that won't work, simply use a port forwading service.
Added at: 2005-02-02 19:24