I have received several reports this morning about mail being blacklisted originating from the IP address 173.247.240.251. This appears to the mail server in use at the hosting as of 8am GMT this morning; Tuesday 15th of November 2016.
I have escalated this and reported it back to the hosting company along with some example error messages. Generally what happens from here is they will change the IP address of the mail server and this will clear the problem. As at 10:30am the blacklisting is still in place.
If you are experiencing problems with mail this morning, and you can see the text 173.247.240.251 in the message that has been returned, that is the problem I am currently pursuing with technical support.
-Mark
See this article for more information on blacklists.
11:10am Problem has been reported to second line support at the hosting company and they have replicated it, so they are aware of it. What they will do now is assign a new IP address to the mail server which will take a little time to propagate. Once it has propagated around the internet then normal service will be resumed.
I will try sending a message later this afternoon to confirm the system is operating normally.
12:50pm I have just sent a mail from my address to my BT address and the message was sent without any errors. So at this time it looks like the problem has been resolved and mail is behaving normally now.
(Closed) …….. (Reopenned at 18:15hrs)
After the mail server address was changed there were a number of other bounce back messages received based on the new server address during the afternoon. I saw one, and another group saw some as well. Although the problem was not as bad as it was earlier in the day. I got back online to support at 18:15hrs, spent another 30 minutes on a support call. They managed to replicate the problem again and have subsequently changed the IP address yet again (3rd time in 24hrs).
08:00 Weds: I received a message overnight indicating that the system should be working ok now.
Why do they keep changing the mail server address?
Blacklists and reputation lists generally work on the basis of the IP address of the server. So if the mail server appears on one, the easiest and most effective thing to do is change the IP address of the mail server which automatically removes it from blacklists unless the problem persists of course, in which case it will end up on another one. I am not sure what happened yesterday as these systems are generally very stable and predictable which is why I chose this host. I am asking some questions about it once the dust settles.