Is your ISP blocking outgoing port 25?

Dave Pooser dave.nanog at
Sun Jun 21 00:45:53 UTC 2009

>> On the other hand, why don't modern mail user agents and mail transfer
>> agents come configured to use MSA port 587 by default for message
>> submission instead of making customers remember anything?
> Better yet would be for the MUA to probe for the "best" configuration.

The iPhone mail app will try 587 and then fall back to 25 if 587 doesn't
work, which strikes me as a model for others to emulate.
Dave Pooser, ACSA
Manager of Information Services
Alford Media

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