dnsbl
A friend warned me of a scenario that could have the potential to freak people out, if misunderstood. It looks like this:This person is using Spamhaus to filter inbound mail.They seem to be rejecting mail from Gmail due to a Spamhaus listing.The Spamhaus website DOES suggest there might be an SBL entry (a blocklisting) for Gmail.So…Spamhaus is blocking Gmail? NO, no no. Gmail is not blocklisted by Spamhaus. Promise. Here’s what’s actually happening.Using Spamhaus is good, but querying Spamhaus using open/public DNS resolvers is bad. Spamhaus is actually rejecting those queries — they’re not blocking mail from Gmail. The person running into this problem needs to switch over to using the Spamhaus DQS (Data Query Service), and that ought to just flat out fix things.As noted above, the rejections are actually because the email administrator of the mailbox provider or mail server in question has configured Spamhaus in a way