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Blocking Competition

Members of the ISP-Tech list say that a rule that is now imposed on subscribers by most local phone companies across the globe (even in Mexico) is preventing ISP choice.

[August 5, 2002]

On the ISP-Tech list in July, JB inquired,

"I work for an ISP in Mexico city. To keep their network from being used as an open relay, the big ISP in town, Telmex, recently changed the way they let users send e-mail. Some of our customers buy DSL service from them and host their web sites with us, but now that Telmex won't allow customers to use their SMTP if they don't have the domain hosted with them, our users are blocked. Any advice on how to handle this?"

A number of respondents noted that this is an increasingly common restriction:

[PM recalled] "Verizon did this with their DSL a while back, checking the 'from' address to make sure it was from one of their domains."

[JL added] "It's actually quite common here in the US, and will probably soon be the default with most ISPs. We've been using the very same restrictions for years, and for the same reason."

[SZ agreed] "I know of two other providers that have started to do this. It's really annoying for clients who are using other providers for e-mail."

Others suggested playing by the rules, and simply changing the reply-to address:

[PM advised] "A solution that might work is to set the 'from' address to a valid account@telmex address, set the 'reply-to' address to user@domain, and use Telmex's mail servers."

[JL agreed] "Configure the 'from' address to be a 'legal' e-mail address on whatever SMTP server you're using, then configure 'reply-to' to the address to which you want replies to be sent. Typically, that works just fine, and your correspondents never know the difference, because when they hit 'reply,' it goes back to the right place."

JB explained that it's not that easy when working with Telmex:

"They are checking the 'reply-to' address as well-if it's not one of theirs, they reject the message."

Others discussed the possibility of simply changing the ports used for e-mail:

[TM asked] "Have you considered using a non-standard port for the outbound e-mail? Some e-mail clients allow you to specify what port to use. This may sound like a tech support headache, but what ISP is going to block all outgoing ports and break every Internet-related program?"

[SV countered] "As a LAN admin, I always block every port that my approved applications aren't using. I suspect that getting the customers to go along with this approach simply isn't going to fly."

VS offered another possible solution:

"Consider using SMTP over SSL on port 465, which is a valid port-it's worked for me. Use the Stunnel program."

—End