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Help me argue against AT&T blocking my outbound SMTP traffic

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#1 SirEvan

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Posted 06 August 2013 - 17:20

For about 6 months, I've had two lines coming into my house.  AT&T (Uverse) for TV, phone, and internet, and Comcast Internet Only (had a great deal on it).   Comcast recently jacked up the rate due to a promotion ending, and I don't want to pay 65$ a month plus the 200 something for AT&T, so I'm dropping Comcast.    I have a number of machines on my network, that I've switched over to the AT&T line (just plugged the router they were connected to to the AT&T box).   and now I find that I'm having trouble sending email from Exchange.

 

 

Before when I was on comcast, I had no issues sending/receiving from Exchange to gmail, yahoo, etc.  The moment I swapped the line, I could only receive, but not send.    I did some research and saw that it looks like AT&T Uverse blocks SMTP traffic, so I called up AT&T and first got the Philippines, which was no help, then I got someone in India, who didn't even know what Exchange was.   They claim they don't block any ports (except neither could tell me what port SMTP ran on), yet when I try doing some basic tests, I get failures.

 

Here's what I know:

 

1.) So far, can only successfully send to the AT&T account they set up.  Gmail, my work email, yahoo...nothing else works.  No problem receiving inbound email though

 

2.) nslookup for gmail:

C:\Users\Administrator>nslookup -query=mx gmail.com
Server:  www.asusnetwork.net
Address:  192.168.0.1


Non-authoritative answer:
gmail.com       MX preference = 5, mail exchanger = gmail-smtp-in.l.google.com
gmail.com       MX preference = 20, mail exchanger = alt2.gmail-smtp-in.l.google.com
gmail.com       MX preference = 10, mail exchanger = alt1.gmail-smtp-in.l.google.com
gmail.com       MX preference = 30, mail exchanger = alt3.gmail-smtp-in.l.google.com
gmail.com       MX preference = 40, mail exchanger = alt4.gmail-smtp-in.l.google.com

If I ping these, i get a reply, but if I try to telnet to any of them against port 25, I get timeouts.  

telnet smtp.gmail.com 25
Connecting to smtp.gmail.com...Could not open connection to the host, on port 25: Connect failed

So I try using one of AT&T's servers

telnet frf-mailrelay.att.net 25
220 att.net - -Maillennium ESMTP/MULTIBOX frfwmxc14 #1036

I then try SMTPS on gmail:

telnet smtp.gmail.com 587
220 mx.google.com ESMTP g1sm2482249oeq.6 - gsmtp

so SMTPS works fine, but not SMTP.  telneting to smtp.gmail.com 465 also seems to connect, but gives me a blank screen

 

Last but not least, I grab a vm thats running ubuntu behind the AT&T box, and run tcptraceroute.  results:

evan@apt-proxy:~$ sudo tcptraceroute smtp.gmail.com 25
Selected device eth0, address 192.168.0.113, port 56215 for outgoing packets
Tracing the path to smtp.gmail.com (173.194.79.109) on TCP port 25 (smtp), 30 hops max
 1  192.168.0.1  0.431 ms  0.340 ms  0.376 ms
 2  192.168.1.254  1.484 ms  0.901 ms  0.703 ms
 3  * * *
 4  * * *..... (and so forth)

so it's clear that it dies right outside the 2Wire box from AT&T.   

 

Besides this, is there anything ELSE i can try to get more evidence against at&t?  I found this link http://forums.att.co...ed/td-p/2544419   that seems to help, but the links to the at&t social media connect guys doesn't work.  I'm just looking for any more tests I can do to prove AT&T is blocking port 25 outbound.




#2 Anibal P

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Posted 06 August 2013 - 22:10

I've had U-Verse and my Mom has had it too, we've never had any issues sending emails, Gmail or Exchange emails

 

Your issue is possibly something else, I would start at your router config, possibly redo it, so far I doubt the problem lies on AT&T's side, not yet



#3 vcfan

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Posted 06 August 2013 - 22:25

im pretty sure you don't need to prove they block port 25,because they probably do and will happily admit it. some ISPs block this outbound port to stop spammers from using their network to send mail. if you call them, you shouldn't have a problem with them unblocking it,they most likely will.



#4 Forjo

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Posted 06 August 2013 - 22:36

im pretty sure you don't need to prove they block port 25,because they probably do and will happily admit it. some ISPs block this outbound port to stop spammers from using their network to send mail. if you call them, you shouldn't have a problem with them unblocking it,they most likely will.

Good luck with that.

 

AT&T does in fact block port 25 outbound. And if you tell them you're running and Exchange Server they'll probably tell you that they don't support servers on their home service.

 

Switching to a business account will allow you to unblock the port -- but that may cost more.

 

I'm actually surprised because Comcast does the same thing. They'll unblock it for you, but it'll re-block at a later date automatically. My business partner has Comcast (I have Comcast Business) and this has been our experience.

 

Unless something has changed, AT&T won't unblock it -- it's one of the reasons I dropped DSL as my backup ISP.

 

-Forjo



#5 +xreyuk

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Posted 06 August 2013 - 22:45

Are you sure they don't want you to use their SMTP servers instead of your own?

 

I know this has previously been common with ISPs in the UK, until, like yourself, people had problems and didn't know how to change their SMTP servers.



#6 OP SirEvan

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Posted 06 August 2013 - 23:02

Are you sure they don't want you to use their SMTP servers instead of your own?

 

I know this has previously been common with ISPs in the UK, until, like yourself, people had problems and didn't know how to change their SMTP servers.

 

ATT's smtp servers telnet fine...everything else doesn't, combine that with the 587 working on google, but not 25, along with successful internal telneting to my smtp port, along with the fact that the only thing i did was move my router over to the AT&T uverse modem (verified uverse firewall was set to allow 25 out), leads me to believe in fact they are blocking it.   I'm going to have to try and get the supreme leader of tech support on the phone because everyone I talk with has no clue what SMTP, Exchange, or anything else remotely technical is.  "Oh let me run some tests on your modem"



#7 +xreyuk

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Posted 06 August 2013 - 23:26

Got to love good ol' generic tech support :D



#8 vcfan

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Posted 06 August 2013 - 23:36

Good luck with that.

 

AT&T does in fact block port 25 outbound. And if you tell them you're running and Exchange Server they'll probably tell you that they don't support servers on their home service.

 

Switching to a business account will allow you to unblock the port -- but that may cost more.

 

I'm actually surprised because Comcast does the same thing. They'll unblock it for you, but it'll re-block at a later date automatically. My business partner has Comcast (I have Comcast Business) and this has been our experience.

 

Unless something has changed, AT&T won't unblock it -- it's one of the reasons I dropped DSL as my backup ISP.

 

-Forjo

 

hes not running a server,he just wants to send mail. his email client is sending a request to his mails smtp server to connect,but since outbound port 25 is blocked,no connection can be made. hes not opening a port of his end or hosting any services, at least according to his post. some isps will open the port for their clients,its just closed by default.



#9 +Xenosion

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Posted 06 August 2013 - 23:56

I have Uverse (residential) and also run Exchange. AT&T absolutely blocks port 25 by default. You can definitely have them remove the block though. I have done this for myself and a few clients as well. I used to have a direct number to tier 2 support and they would immediately know what I was talking about and removed it. It's a simple check box on their end.

 

I haven't read the whole thread just felt like sharing.



#10 srbeen

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Posted 07 August 2013 - 00:24

 

I used to have a direct number to tier 2 support and they would immediately know what I was talking about and removed it. It's a simple check box on their end.


Exactly. Call and get the tech dept and ask for tier 2/level 2 tech support from the get and they should forward you. They may be 9-5 scenario compared to 24hr callcenter but they know what they are doing. I do this with my internet co (actually level 4 if you can believe it) and they have no problem talking technical mombo jumbo and helping you with specific issues.

#11 Lewism

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Posted 07 August 2013 - 00:43

ISPs usually block port 25 to stop spam except for their own SMTP (AT&T SMTP in your case). If your computer is infected with a virus, it could be turned into a spam server.



#12 Forjo

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Posted 07 August 2013 - 00:49

hes not running a server,he just wants to send mail. his email client is sending a request to his mails smtp server to connect,but since outbound port 25 is blocked,no connection can be made. hes not opening a port of his end or hosting any services, at least according to his post. some isps will open the port for their clients,its just closed by default.

Oh? He specifically mentions Exchange. If he doesn't have an Exchange Server he should be connecting via ActiveSync or RPC over HTTP. Either way SMTP wouldn't be used and wouldn't be a problem.

 

-Forjo



#13 OP SirEvan

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Posted 07 August 2013 - 01:00

hes not running a server,he just wants to send mail. his email client is sending a request to his mails smtp server to connect,but since outbound port 25 is blocked,no connection can be made. hes not opening a port of his end or hosting any services, at least according to his post. some isps will open the port for their clients,its just closed by default.

Heh... I am running Exchange.  worked great on comcast..not so much on att.  Guess im gonna have to call them AGAIN.  ugh



#14 Roger H.

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Posted 07 August 2013 - 01:06

Surprise your Exchange works in that mine doesn't even allow "residential IPs" to connect over port 25. If you aren't static and trying to use 25 you get blocked, only 587 or 465 will work for residential IPs. This Is standard I thought to even Gmail and such. So I'm surprised you can send/receive emails on a dynamic IP range.



#15 jsterling

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Posted 07 August 2013 - 01:27

I've had this problem with several employees on ATT using our business email from outlook.  Just set exchange up to use a different port.  I've setup our mail server to accept SMTP traffic from port 26 which works fine on the ATT network.

 

Their never going to change this policy and if you want to solve the problem just adjust your approach.