What are the ImproWare and SwiNOG blocklists?
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spamrbl.imp.ch and dnsrbl.swinog.ch check IPs, and uribl.swinog.ch checks domains. ImproWare AG in Switzerland handles all three.
What the operator says
"IP addresses from caught spam mails" ImproWare, Antispam, about spamrbl.imp.ch, read 1 Nov 2026.
What it really measures
spamrbl holds IPs seen in caught spam. dnsrbl and uribl are built from spam traps. uribl is different in one way: it lists domains that appear inside spam, not where the mail came from, so your domain can land there if your link is in someone else's spam.
What to think about
ImproWare says this is for email administrators. If you do not run your own mail server, you should never need to ask. We class IMP Spam as low-impact.
How to get off it
Check on the ImproWare page, then ask for removal. It is free and most requests take up to 48 hours. You get one request per IP per week, so fix the cause first.
What "low-impact" means on these pages: the big mailbox providers rarely use the list, so it rarely affects delivery at Gmail, Outlook or Yahoo. It can still point at something worth fixing.
Want a hand getting this delisted? Here is how to write to a list's operator, or ask a person on our free SOS Hotline. Tell us the list and the IP or domain, and we reply within 48 to 72 hours.
A separate job: cleaning your list does not remove a listing. If you also want to know who on your list is safe to send to, clean your first 1,000 free.
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