Can't access mail servers over AT&T U-verse Internet connection

Stumped today at a client site, a home office with several different devices including Mac OS, Windows, iPhone, etc. I was called in to troubleshoot a POP3 connectivity issue accessing mail servers over AT&T U-verse ISP connection. No problem accessing web mail, and ALL of the POP clients stopped working at the same time last Thursday. On his phones, he can access the email accounts over the cell network, but as soon as he gets on his Wi-Fi he loses email connectivity.

This client is paying Verizon for a mydomain account to keep his email addresses even though he is no longer a Verizon customer since moving away from his beloved FIOS connection. The mydomain tech support people confirmed that the client's mydomain account with Verizon was active and in good standing.

From there we connected with Verizon general tech support to verify POP3/SMTP settings. We had the correct settings. This tech went a step further and did some port testing for us and it was his determination that the traffic to the mail servers was being blocked on the AT&T network. On to AT&T tech support. The level 1 tech did a thorough job of checking things out for us and could not find any issues. From there she referred us to AT&T Connect Tech to troubleshoot further. This group insisted that their services were available with prepayment only regardless of where they found the problem to be. This put the customer over the edge (putting it mildly :-), so we didn’t stay with that call too long. My final test was to connect one of client's laptops to my T-Mobile cell phone hot spot. Once I did that, email from came pouring in, proving to me that the problem is on the AT&T network.

We could not get any resolution from the techs we talked to, so that's where I had to leave it. I did some reading in the Verizon user groups and it appears others have had similar issues but it's not clear how or if they were resolved. Any ideas on what's going on would be appreciated and particularly how to get past the issue.
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tcianfloneAuthor Commented:
Oh, I did of course reboot the U-verse gateway. Also perused the included firewall settings and didn't see anything obvious.
Although not all ISP's do this, a few years (5-10) back most of them started blocking all POP3 and SMTP (tcp port 110 and 25) traffic to servers that are NOT on their network, unless you had a business account.  This one small step in many to help reduce spamming.

I'm not sure if Verizon's pop3/smtp servers support SSL but you may want to check.  I'm not sure if ISP's block the SSL'ed POP3/SMTP ports as those typically require authentication.

Today, mobile carriers will NOT do this.  Even though technically they are an ISP for your phone they don't provide e-mail services for you and they know that 99% of the time your "normal" e-mail account is not with them.  That is why it works on your cell phone.
Look in the advanced settings? Are you using secure connections (SSL) for the servers? The ports should end up as 995 for POP3 and 465 for SMTP.
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Pretty much what Verizon says you got to do:

As for ATT,it has been my experience as a contractor that anything they say or do ,needs to be checked a couple of times.

They can be morons with a capital M.
tcianfloneAuthor Commented:
I've been on a lot of calls over the years where what user giltjr posted was exactly the case. I was assuming that this call was one of those, where the email clients were set up with incoming/outgoing ports 110/25 and I would just update the clients to use SSL and that would be that. Unfortunately, not the case here. As I documented in my post, I verified the pop/smtp settings with the vendor. They are correct. And in fact they worked fine once I put the clients on a different ISP connection. As an update, the customer had AT&T on site the day after I was there. They were NOT able to get it working. My guess is that this has to be escalated to network operations for resolutions. How you do that in a company as large as AT&T I have no idea.
Try calling a couple of more times.

You may eventually get somebody that knows their butt from their elbow.

ATT is not a very good ISP.
I will bet $$ that they will try to offer a move to a business account in order to fix this. Cause I doubt that their engineers will have a major interest in chatting. However, since you've proven that AT&T is actually blocking this, I would try pressing them. But you're probably going to have to force escalation to a level 3 person or a manager. The level 2 person will more likely understand what you're describing, even if they try to deny it. But the level 3 person or manager is the one who is going to do the most to really get things accomplished.
My experiences with ATT :

Customer had DSL line that had the dslam moved without their knowledge to a different location.
Internet was moving at a crawl,it took about 10 or 15 calls till I got somebody that knew that.
Their solution was to deal with  256 kb data stream or go with T1.

Was told by ATT installer on another site that when the sun goes down ,the DSL service will suck because they turn the T1 signals up and they bleed into the DSL lines.
At least he was honest.

If you can find another ISP...
tcianfloneAuthor Commented:
I'm closing this question with no resolution. The client also tested one of his laptops on a friends Comcast network and it worked fine there. Client is likely going to drop AT&T in favor of Comcast. Thanks for you input.

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Sorry, but the resolution is that AT&T blocks the ports you are trying to get to.  The level of support at AT&T you are talking to may not know this, but that is what is going on.
tcianfloneAuthor Commented:
Isolated the problem but no resolution.
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