554 5.7.1 Service unavailable; Client host [154.0.***.**] blocked using zen.spamhaus.org; https://www.spamhaus.org/sbl/query/SBL289647
SMTP error from remote mail server after pipelined DATA: 550-197.242.**.*** listed at zen.spamhaus.org
You’d seen these error messages in your mail server, if your IP address has ever got listed in Spamhaus SBL. Getting blacklisted in SBL is a concern for many web hosts, as it often leads to customer complaints about mail delivery failures.
Our engineers fix Spamhaus issues everyday in their role as Outsourced Support Specialists for web hosting providers. Since Spamhaus checks only for their SPAM criteria, we’ve seen that even perfectly legitimate business mails were tagged as spam. (more…)