SMTP Blocking

by on November 15, 2007 · 17 comments

In response to a post I did on Verizon’s obnoxious DNS policies, a Techdirt reader writes:

Verizon DOES block your ability to use 3rd-party mail servers. GMail is web-based, son. A server at a friend’s ISP, connecting over port 25, is BLOCKED by Verizon, period end of story.

Now, I use another port and so go my merry way, but Verizon, having blocked port 25, can block any ports they wish under the same guiding principle. Verizon sets limits.

And another reader responds:

Isn’t that standard practice? To (somewhat) prevent spoofing email, ISPs require outbound mail to go through in-house servers, but inbound on port 110 can be any source you have access to.

Does anyone know if this is true? I’ve occasionally encountered Wifi connections in hotels or coffee shops that block outbound SMTP, but I’d always assumed that real residential ISPs don’t do that sort of thing. Such a policy does little or nothing to combat spam, but it sure is a pain in the butt for those of us who use real mail clients and don’t use our ISP’s SMTP servers.

Relatedly, would such a policy a violation of network neutrality? It sure seems like it violates the letter of Snowe-Dorgan, which would imply that thousands of annoyingly-configured hotspots would instantly become illegal if network neutrality regs passed.

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