SMTP problems from *.ipt.aol.com

Sat Jan 17 02:54:06 UTC 2004

Christopher X. Candreva  [1/17/2004 5:02 AM] :

> On Fri, 16 Jan 2004, Ajai Khattri wrote:
> 
> 
>>I have several users who connect to our mail server from an IP in the
>>*.ipt.aol.com namespace. All are complaining about intermittent SMTP problems.
>>I see that outbound SMTP traffic is proxied through AOL servers to our mail
>>servers. Has there been a change recently causing this to not work?
> 
> 
> We had users who SMTP AUTH relay through us from AOL dsl lines suddenly have
> problems this week. Switching them to the submission port (587) has solved
> things so far.

You just noticed this now?

AOL has, since the past several months (over a year I think) set up 
their dynamic IP pool *.ipt.aol.com to hijack port 25 outbound requests 
and reroute it through a set of their own mailservers, that do some 
elementary rate limiting and filtering.

http://postmaster.info.aol.com/info/servers.html says these are the servers:

rly-ip0[3-5].mx.aol.com
IP Address Server
64.12.138.7 rly-ip03.mx.aol.com
64.12.138.8 rly-ip04.mx.aol.com
64.12.138.9 rly-ip05.mx.aol.com

As Chris Candreva said, have your users use the MSA port 587 to submit 
their email.

And blocking the rly-ipXX.mx.aol.com servers might be a good idea, 
depending on your situation.

My experience has been that you'll see a lot more intercepted direct to 
MX spam attempts and virus payloads than you'll see mail from road 
warriors dialing into AOL and trying to smarthost through their ISP / 
corporate smtp servers.

	srs

-- 
srs (postmaster|suresh)@outblaze.com // gpg : EDEDEFB9
manager, outblaze.com security and antispam operations