google public dns
You’ll recall me warning recently that using Spamhaus data to protect your mail server is a bad idea if you’re using open or public DNS resolvers. TL;DR? Spamhaus is worried about too much traffic via public channels but blocking is implemented in a way that makes it effectively intermittent and potentially confusing. You could be fine for weeks and then suddenly you start bouncing all inbound mail accidentally. Or you could be querying a resolver that never shows ANY bad IPs to block, losing you out on the good spam filtering benefit that you were hoping for.Here’s what to do about that.No matter how you implement DNSBL usage, check your logs periodically. In the case of Spamhaus, look for the “127.255.255” response codes. That will indicate that your attempt to query Spamhaus data is being blocked, so you’ve got a problem. That problem is probably interfering with the delivery of…
Do you use any of the Spamhaus blocking lists (DNSBLs) to protect yourself from inbound spam and email threats? If so, you’re not alone. The Spamhaus data is quite popular and used by many ISPs as a front door gatekeeper for IP (and domain) reputation.If you do use any of Spamhaus’s DNSBLs, though, make sure you’re not doing it via a public DNS resolver or via any DNS server that is attempting a high volume of queries against Spamhaus without being registered with them. If you do, you risk the queries triggering blocks simply due to the sheer volume of DNS traffic Spamhaus is receiving. Meaning you’ll end up blocking mail that wasn’t spam and that you probably didn’t mean to block.Here’s how to catch that. Look in your server’s mail log for response codes or response text from Spamhaus queries. For text responses, look for things like “Error: open…