Even a perfectly built email will not be delivered if it comes from a sender that inbox providers distrust. The Blacklist tab checks the sending domain and IP behind a captured message against well-known DNS blacklists (DNSBLs) so reputation problems surface during testing, not in production.

For each blacklist, MailSandbox reports whether the sender is listed, so you know before launch whether your sending infrastructure needs attention.

The check queries a range of widely used DNS blacklists, including:

• Barracuda Reputation Block List
• SpamCop
• PSBL (Passive Spam Block List)
• SORBS
• Backscatterer
• NiX Spam, Lashback and others