Comcast email bounces

[blu at vl.com (Tom Metro)]

John Chambers wrote:
> Our ISP is speakeasy, and she managed to talk to a CS person
> on  Sunday  who told her that comcast had been doing to this to email
> coming via at least one of speakeasy's servers, but not all of  them.

Have you determined whether it is an internal black list they are using 
or if they are using one of the public lists. If the latter, you might 
be able to get Speakeasy to take the steps necessary to get their server 
removed from the list.

Were you able to determine what event caused the Speakeasy server to be 
added?


> Any ideas about a workaround until it gets fixed?
...
> it seems that speakeasy only  advertises  mx.speakeasy.net  as  their
> mail server...

mx.speakeasy.net is indeed listed as the mail exchanger for 
speakeasy.net, but that is for inbound mail, and if I understand your 
situation correctly, you're looking for an alternate outbound relay server.

There's no special DNS record type for outbound relays, but most ISPs 
use mail.example.com or smtp.example.com for that purpose. In this case 
Speakeasy appears to use mail.speakeasy.net. Unfortunately it appears to 
use some sort of load balancing scheme, as you noted above for the MX 
server, and thus always returns the same IP. However, connecting to it 
exposes some additional information:

% telnet 69.17.117.59 25
220 mail2.sea5.speakeasy.net ESMTP  bWFpbC5zcGVha2Vhc3kubmV0

That exposes the naming pattern they use for their individual servers, 
and those individual servers appear to have publicly routable IP addresses:

% host -t a mail3.sea5.speakeasy.net ns-sea.speakeasy.net
mail3.sea5.speakeasy.net has address 69.17.117.5

% host -t a mail4.sea5.speakeasy.net ns-sea.speakeasy.net
mail4.sea5.speakeasy.net has address 69.17.117.6

% host -t a mail5.sea5.speakeasy.net ns-sea.speakeasy.net
mail5.sea5.speakeasy.net has address 69.17.117.7

% host -t a mail6.sea5.speakeasy.net ns-sea.speakeasy.net
mail6.sea5.speakeasy.net has address 69.17.117.8

etc...

and are reachable:

% telnet mail6.sea5.speakeasy.net 25
220 mail6.sea5.speakeasy.net ESMTP  bWFpbC5zcGVha2Vhc3kubmV0


So the workaround is to alter your mail client's SMTP server setting to 
use one of these individual servers (one that isn't blocked by Comcast), 
with the understanding that this will reduce the your long term 
reliability as you'll always be communicating with a single machine. 
(You can always switch back to the main address after the block expires.)

If this is an ongoing problem you can purchase mail relay service from a 
third party for a nominal annual fee. A few providers have been 
mentioned in the BLU list archives.

  -Tom

-- 
Tom Metro
Venture Logic, Newton, MA, USA
"Enterprise solutions through open source."
Professional Profile: http://tmetro.venturelogic.com/