How Pervasive is ISP Outbound Email Filtering?

Erris writes "A member of the Baton Rouge LUG noticed that Cox checks the text of outgoing email and rejects mail containing key phrases. I was aware of forced inbox filtering that has caused problems and been abused by other ISPs in China and in the US. I've also read about forced use of ISP SMTP and outbound throttling, but did not know they outbound filtered as well. How prevalent and justified is this practice? Wouldn't it be better to cut off people with infected computers than to censor the internet?"

Comments

Kudos to Cox Communications

[merc]

I would like to first state that I am a Cox cable internet subscriber in the Phoenix area. I also happen to wear the abuse desk hat for Arizona's oldest ISPs.

I can say without question that the amount of spam we get from cox is almost NIL. I constantly see spam coming out of Comscat's network, also Verizon and from time to time Time Warner but RARELY Cox. In fact I can't remember the last spam I received that originated from their network.

I don't mind that my egress SMTP port is blocked forcing me to use a MSA (mine is configured to use SMTP AUTH with TLS, which works nicely). The fact is that Cox has their act together in my opinion. The fact that they are a white hat in the abuse category makes me want to continue doing business with them. I don't think what you're seeing here is intentional censorship. It would actually be irresponsible for Cox not to filter outbound mail traffic, since they are bound to have customers that run malware infected / zombied host computers.

Anyway, I say "good job Cox" :)

P.S. I work for an ISP that is NOT Cox--which one might think after reading my glowing statements (in fact we compete against Cox)