Sorry - I have included in an earlier reply after being prompted by another member - but I guess it can got lost with all the replies in this thread. And it doesn't have anything to do with the Contabo address my emails are coming from - it's on a different provider/subnet. The IP is 51.155.244.89


On 18/04/2024 18:31, Michael Peddemors via mailop wrote:
It's REALLY hard to give you good advice, if you don't include the actual IP Address that is listed..

However, if it is the same email server you sent from, it's on Contabo which has it's own problems with reputation.. And I don't think they really care to help the innocent operators on their networks with reputation problems..

On 2024-04-18 03:52, Sebastian Arcus via mailop wrote:
I hope this is within the allowable topics for this list. I tried searching the archives, but haven't found an answer for the issue below yet. If anyone could shed some light, it would be very much appreciated.

A few days ago I started having issues with the public IPv4 address of one network I look after ending up on the Spamhaus XBL and CSS blacklists. I have taken good hard look at the setup and applied to be delisted twice, but it is blacklisted again - so I must be missing something. I read through the Spamhaus docs on their website. The following applies to this site:

1. Port 25 outbound is completely blocked for the entire network, except our inhouse email server which uses Exim
2. The inhouse server doesn't do any sort of relaying.
3. The site doesn't do any sort of marketing or mailing list type activity as far as I know - and the Spamhaus detected connections are out of working hours - so this being caused by employees sending any unwanted emails seems unlikely. 4. I have checked the Exim logs, and there is no sign so far it has been compromised in any way, or it is sending out any unusual email traffic. 5. This is a low volume site - I would say less than 100 emails sent per day. 6. Spamhaus provides the date and timestamp of last rogue connection detected - but there is nothing in our Exim log which matches that date and time.
7. The information they provided is:

(IP, UTC timestamp, HELO value)
<our.public.ip> 2024-04-18 05:25:00 <our.exim.fqdn.and.helo>

The wording on Spamhaus' website is a bit generic, and seems to hint that you can end up blacklisted if infected with a variety of other viruses/exploits, not only those to do with smtp. However, because of the format of the info above, I was digging in the direction of an exploit which uses the smtp protocol to spam the internet.

Does anybody here have some experience with Spamhaus blacklists? Am I barking up the wrong tree, and should I cast the net wider, and look for any type of infection which scans any other ports on the internet - not only the type which would be scanning smtp servers on port 25 trying to send spam? In our case that should be technically impossible, as port 25 outbound is blocked completely on the gateway/firewall (except for the email server)? Grateful for any hints - as it would be useful to narrow down a bit what am I looking for.
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