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Today, my SMTP server (running on AWS EC2) rejected my connection from my mail client, because my home IP address (dynamic, but it's been the same for months — possibly years) is listed in Spamhaus — specifically Spamhaus CSS. The last email I sent from here was about 17 hours ago, so it's been added in that time. FWIW, MxToolbox does not (yet) indicate that the address is on any other blacklists.
Based on suggestions from other sources, I've checked that spammers haven't hijacked my ISPs BGP feed — it appears they have not. Announcements have been static for 11 months, so it's nothing that nefarious.
I don't run an email server from behind that IP, so, my concern is that something on my network somewhere is infected. I'm not sure if it would be better or worse, but another possibility is that my ISP's whole block of addresses has been listed.
Of course, I could just submit the form to have myself removed. Or, since I run the SMTP server, could whitelist my IP ... but I'd rather get to the root of the problem, rather than potentially papering over something serious (e.g., my home router has been pwnd and is spamming the world).
What's the best set of steps to go about diagnosing exactly why I was blacklisted, so I can diagnose what caused it?
philolegein
Posted 2019-05-06T14:27:12.823
Reputation: 31
Are you completely sure it was the CSS and not the PBL? – user1686 – 2019-05-06T14:29:02.580
1Quite literally - many spam blacklist block every dynamic ip address for mail they can – Journeyman Geek – 2019-05-06T14:29:27.343
@grawity, Mac Mail pops up the following when I try to connect to the server: Cannot send message using the server <my remote server>: Verify that you have addressed this message correctly. Check your SMTP server settings in Mail preferences and verify any advanced settings with your system administrator.
The server response was: Service unavailable; Client host [my home IPv4 address] blocked using sbl.spamhaus.org; https://www.spamhaus.org/sbl/query/SBLCSS