Backscatter

It happens when a server accepts a message and only later decides it cannot deliver it, then sends a bounce to the sender address on the envelope. If that address was forged, the bounce goes to someone who sent nothing.

Rejecting bad recipients during the SMTP conversation avoids it.

Receiving servers that accept everything and bounce later contribute to it; a catch-all setting is a related pattern worth flagging.

• Email authentication
• Autoresponder
• Verify a list
• Topic: Spam and blocklists
• Topic: Email deliverability
• All terms