06-04-2017 6:17 PM
Been running an exchange 2010 server over assigned static IP address for years now. We moved to new location and transferred service receiving new IP address. Everything worked fine for last few months. As of June 1st all traffic started being blocked outbound over port 25. This is a business account not residential. How do I get help resolving this. I can telnet through port 587 to all the email servers that are stuck in my exchange queues. If I try to telnet over port 25 it will not connect. I am not on any block lists and the server has been locked down from being a relay server for years now. No settings changed server side. All test say ISP is blocking port 25. Please help we need to be able to send our emails to operate as a business.
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06-04-2017 7:56 PM
Seeing the same thing on my Linux mail server and static dsl that has been a mail server on that ip for over a decade. The last successful sent email was 1:52am Central on June 1.
I'm actually seeing an ICMP Type 3 Code 13 from an upstream AT&T IP address that's shutting down the connection attempt.
Two unseuccessful support calls. Let me know if you figure out the process to fix this.
06-04-2017 8:03 PM
In the private message, provide your account number, best way to contact you and explain that your account did not have the TCP Port 25 block (SMTP) until last Wednesday and now it does, and ask that it be removed again.
06-04-2017 8:13 PM
Thank you for your follow up JefferMC. I will do as you suggested and post back if it gets resolved.
06-05-2017 8:21 AM
Whoever made this decision and wasted hours of time for IT admins, AT&T support personnel, and users deserves to be FIRED!!!! You cant block a well-known port as an ISP especially SMTP!!!
06-05-2017 9:30 AM
Same issue. Problem seems to have started at 9 am Pacific on June 2. I was just alerted to it and am rushing to address it.
06-05-2017 11:17 AM
I just talked to someone in support who told me that this is an effect of splitting from Yahoo. She tried to convince me that "ATT has never supported port 25" and that I just need to enable SSL. Uh, no. So at the moment I'm stuck. I'm investigating switching ISPs, but until that I'll see if I can relay off a rented VM.
06-05-2017 11:19 AM
The support systems at AT&T are the worst I've found anywhere. Other places at least have a tech support chat so I'll have a printed log afterwards. They usually have a trouble ticket system.
06-05-2017 12:35 PM
Was told a technician was looking into unblocking the port on my IP address and I would be updated as soon as there was more information. 3 and a half hour later and I'm still trying to patiently wait. Still will update if this method brings me to the solution. Stay strong people... stay strong
06-05-2017 1:14 PM
06-05-2017 1:37 PM
Based on what they are seeing, I had already had the smtp block removed years ago.
At a network level, I'm seeing an AT&T IP at 18.104.22.168 respond with an ICMP packet that shuts down the connection attempt (ICMP Type 3 Code 13) every time I try to make a port 25 connection.
I think that somewhere in the AT&T hierarchy, something new has been switched on and few at the support side of things are aware of this new thing.
06-05-2017 2:27 PM
AT&T has a bunch of ports they block to control DDoS attacks. This is likely a new initiative along those lines. It may have been poorly thought out.