Teacher
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13 Messages
SMTP outbound blocked
Got U-Verse + Internet. Specifically asked if it was ok to run my own e-mail server (sendmail: personal use, personal domain, no hosted, no relay). Was assured it was fine to do so, and that AT&T would setup my DNS PTR record for my static IPs.
Had to call in to remove the block on outbound SMTP (tcp 25). They removed it, no problems for months.
Recently lost connectivity all day, think nov 2nd. Outbound SMTP has been blocked again since. Obviously an AT&T network problem. "telnet
Uverse tech support level 2 tells me that outbound SMTP is not blocked, and that I should call Connect Tech.
Connect Tech tells me that it's an obvious network problem and I should call DSL tech support.
They refer me back to connect tech, who refers me back to tech support. Over and over... all darn day.
What can I do? I can't get anyone to escalate this issue to anyone that even knows what "SMTP" is. I've had people try to walk me through setting up 'the outlook' (*sigh*... I don't even use windows let alone 'the outlook'). I had one tech insist that I *HAD* to use Yahoo webmail and that makes port 25 work. (Really?)
So frustrated.
I know my stuff, I'm a high-end Linux and Network guy by trade.
I know AT&T is still blocking SMTP out. I can't seem to convince anyone of this and just get the constant ping-pong between dsl tech and connectech.
There's just GOT to be some way to get this escalated beyond all these low-end call center reps. Suggestions? Anyone have a magic phrase that gets you past the connect-tech <--> dsl support loop?
alt_phil
Teacher
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13 Messages
13 years ago
Hah...
Sure, you can have your mailserver bind to whatever port(s) you'd like. But it does no good.
Port 25 is what all mailservers use to communicate across the 'net. Listening on port 26 does you no good as no one else is going to send you mail by that port. Sending mail out port 26 won't get get anywhere, because no one else listens/sends on 26. 26 isn't even assigned to a protocol per IANA.
So if port 25 outbound is blocked by my ISP, my mailserver (which is my MTA/MX) can not send mail to the rest of the world. Sending or listening on port 26 does no good because no one else uses it. Your mailserver works because... wait for it... you're using port 25. Same as mine... and everyone else's.
Now sure, if I was using some other MX/MTA as a smart host to relay all my mail off, and I had control of that server too, I could configure it and my mailserver to talk to each other along non-standard ports. But I don't need to, nor would I really want to unless I didn't have control of my PTR record or something. In THAT case, I'd use a standard SMTP TLS port like 465 or 587 and secure that communication.
Regardless, that upstream MX/MTA relay would still need to be able to send/receive on port 25 itself, so it could talk to the rest of the world's mailservers.
Does that "It won't work" post make more sense now?
See... I couldn't send mail out because of the 25 block... sending out 26 (or any other non-SMTP port) wouldn't work, and by standard MXs don't communicate to each other across the Interenet over TLS. That's what we mean by "it won't work."
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SomeJoe7777
Expert
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9.4K Messages
13 years ago
alt_phil is completely correct.
Your mail server might be listening on port 26, but it hasn't received any mail there. Ever.
IMAP uses port 143, TLS is generally paired with ports 465 or 587 like phil said.
Sorry, but you're not going to be able to come into this forum and flash around a few abbreviations and port numbers and be able to convince anyone that you're doing something which is not possible. Plenty of people in here are very familiar with networks and TCP/IP and will call you on that.
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Yrautcnas
Contributor
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2 Messages
13 years ago
Did you have to pay a $29 fee to unblock port 25?
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SomeJoe7777
Expert
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9.4K Messages
13 years ago
There is no fee for AT&T to unblock the port. If you get a technician on the phone who wants to punt you to ConnectTech, hang up, call back, and get a different technician. They will say that when they don't know what you're talking about.
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Yrautcnas
Contributor
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2 Messages
13 years ago
Matt, from U-verse Care, just told me that there is a $29 fee to unblock the port when I emailed this afternoon, and that didn't sound like everything else I was reading. I guess I'll try again.
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SomeJoe7777
Expert
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9.4K Messages
13 years ago
Matt is usually really on top of things. If there is indeed a $29 fee to unblock port 25, that is a newly instated charge.
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ray45
Contributor
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2 Messages
13 years ago
I have been trying to set up my office email on Outlook 2010 with Windows 7 on IMAP since last one week! I got help from our office IT guy . He tried POP# also but did not work. On IMAP I receive my office emails but cannot send out any. Our IT person said AT&T must be blocking the outgoing SMTP due to spam problems. Instead of yahoo servers he used our office servers both for Incoming & Outgoing servers. For Incoming & Outgoing ports he tried various combinations including Incoming of 110 and Outgoing 587 (as well as 25). I talked to ATT support by phone and by chat and they keep on referring me to their paid tech support! Please advise. Thanks in advance! Ray
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alt_phil
Teacher
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13 Messages
13 years ago
The port 25 outbound block really shouldn't bug that many people. Using SMTPS (SSL/TLS) is FAR preferred.
For client-to-server communications, simply checking the box or dropdown or whatever in outlook to use SSL or TLS for SMTP would fix it handily if your mail server is setup to handle SMTPS on 465 or 587 - without the need to unblock port 25. So if that didn't fix it either your server doesn't accept SMTPS or you've got a bigger issue.
AT&T only blocks outbound 25, and a simple call or chat to tech support will unblock it for free. (My case was special as something with my account provisioning was goofed up - BUT the initial unblock of outbound port 25 worked and was handled quickly... and freely)
Just say, "I need port 25 outbound unblocked".
Here's how you can test...
(Forgive me, I'm not a windows guy, so this may not be exact)
First, since you're running windows 7, install telnet.
Then fire up a command window. Either powershell or cmd is fine. Hit windowskey+r for a run prompt and type in "cmd", hit enter or OK. Should see the black command prompt box.
At the command line, type in "telnet 25".
You should almost immeadiately get a blank screen... maybe a banner along the lines of "220 mail.somehost.com ESMTP...". Typing 'quit' and hitting enter should return you to the normal C:\whatever prompt. Should be very quick.
If it just sits there with "trying mail.somehost.com 25..." for a long time and finally fails with connection timed out... then port 25 outbound is blocked.
Test against another mailserver as well. smtp.gmail.com is a good test - it accepts SMTP via 25, 465, and 587.
You should also test telnet to 587 to your mailserver to ensure that works at least. If so... again... checking SSL for SMTP servers should work just fine. AND it's far preferred to use SSL anyways!!!
Of course, disable any software firewall you have on your machine, and try again. The basic Windows firewall will mess with you as well I'd imagine - again, not a windows guy, but you can disable that thing too.
Don't leave the firewall disabled. If that's the problem - you need help configuring your software firewall, and I'm not the guy to help with that. I'm more of a server/network guy... don't even use windows if I can help it. But I'm sure no matter what software firewall you're using you can allow SMTP and SMTPS in it.
Anyway, testing that stuff lets you know where you stand. Testing beyond that gets pretty in-depth as you can see from my earlier posts. I went as far as doing packet captures on both ends and testing many many mailservers. But again... my problem was very abnormal.
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torkyaagba
Contributor
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1 Message
13 years ago
I'm having a similar issue but slightly different (I think). I'm new to networking and all so please point me in the right direction.
I recently registered a domain name and want to host my e-mail services on my computer at home so I changed the A and MX records to have traffic sent to my IP address assigned by ATT. I have Uverse. I downloaded hmailserver and configured it correctly (I think) and set up a few accounts.
I sent an e-mail from my gmail account to the new e-mail I just set up and didn't get a bounceback. However, my server doesn't seem to get the e-mail.
When I ran the "diagnostics" on the server admin and it seems both inbound and outbound traffic on 25 passes through. This is what I get:
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r0d3nt
Contributor
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1 Message
13 years ago
I thought I'd throw in my experience with this since this is the thread that helped me get my similar problem resolved. I at first called U-Verse technical support where after about 12 minutes I was disconnected. I then called back, and their call system clued in on the fact that I still had the problem case open. I was then connected to a specialist who no matter how I tried to explain that I was trying to setup an e-Mail server kept getting confused and was trying to help me with my e-Mail client configuration.
I then decided to try the chat support. I connected with a tech and clearly explained that I was trying to setup a linux server and that I'd read that outbound port 25 was blocked. There were a lot of long pauses, but the tech would look into it and try to open up port 25. I'm not sure exactly what happened, but then the chat software locked up [I was in Linux/Chrome during the chat session]. I was a little annoyed that I got disconnected.
For kicks then I tried sending a test e-Mail simply using mail from the command line. Much to my surprise, it worked! I am now able to send e-Mails from my system[s] without having to worry about trying to authenticate to the AT&T servers with sendmail [such a nightmare configuration wise].
So thanks all in this thread, your advice and insight helped greatly!
-Ubence
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