Top Deliverability’s Blog
Spam Resource: Be careful: Using Spamhaus with open resolvers is bad news
Al Iverson just shared another interesting post on Spam Resource:
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…
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