BT Email server configuration

Question

As there is not yet an email forum I am posting this here in the hope it is relevant. I have also posted an email to the forum moderation team containing some of the non published details from the logs mentioned below.
I have heard from a friend (non-BT customer), running mail systems on their websites, and who has sent me the following comments relating to log entries emanating from BT mail servers.
A non-BT customer is concerned to see that so many BT IP addresses seem to have incorrectly set up mail systems with neither the host nor the HELO set up correctly. The log files show the following error message resulting in the mail not being delivered:-
450 4.7.1 <btcentralplus.com>: Helo command rejected: Host not found; from=<[email protected]> to=<[email protected]> proto=ESMTP helo=<btcentralplus.com>
Could the team have a look at this and comment publicly please, taking this post with the private email to the forum moderation team that was sent at the same time as this message was posted.
Many thanks.
Dorset Vinney - I speak up when I'm worried

Answer 1

Dorset_Vinney wrote:
Thanks for the reply. sorry this is a bit confusing.
My friend has provided the following additional info. It relates to trying to work out the correct settings on a small self-managed business mail server to avoid mail from BT users being rejected. Here is what they say...
I just set up some spam filtering of incoming emaills, one of the checks validates the FQDN and the other looks for valid HELO responses. It looks like all email from BT IP addresses which is not going through the BT-Yahoo mail servers is being rejected on these checks. My concern is that this will result in non-yahoo email from BT users being blocked. Of particular concern is any email which will be sent using a domain based email address as some clients on the mail server are B2B so it is important that these are not blocked by any filters.
Some spam email does get through these checks and is then blocked on IP address by the spamhaus filters. Which suggests that there are valid settings for the FQDN and HELO for some BT users but that the majority are not correctly set up. If it is just the spam malware which is incorrectly set up then this is not a problem. However, as there has been press over the last few years about mail issues from BT IP addresses I do not want to just assume that everything is OK with the current set up and am wondering what whitelisting filters may need to be included to allow valid mail through.
The first paragraph sounds like he expects to get a lot of email from people using their own mail servers on dynamic IP address ranges. This is usually not accepted and many using anti-spam systems will block this. People using "Domain based" systems should set up their mail servers correctly, or use their ISP smarthosts like I do (with the usual address verifcation system, or if business type use inform the mail server hosts to allow it).
This has nothing to do with BT, it is the sender of the emails at fault - which the second paragraph implies, if they are using their own "invalid" mail servers. To me he can happily reject all of these.
Not sure what the "press over the last few days" is supposed to indicate - can you get more detail in this ?
To me it still looks like your friend is trying to accept all spam messages from BT IP addresses, which typically means that the spam is sent directly from a user using a spam created smtp engine. The headers of which will invariably be fake and full of gobble-le-duke.
Not all systems use HELO, some use EHLO ....
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