No sender email is not blocked by default
- Article Number: 000011262
- Products: Forcepoint Email Security Cloud
- Version: All versions
- Last Published Date: September 19, 2018
When trying to block a domain, I could not find the sender email address. When a message arrives with no sender, why isn't it blocked by default?
When a message is received and appears that there is not a sender (or "No Sender" displays), the empty sender field, shown as "<>" is actually defined as "Postmaster" (see RFC2821 for reference). This is mainly used for NDRs and other automated responses.
This means that this type of message cannot be blacklisted, even if the message is spam, as there is not enough information to reject the email based alone on the Sender information.
Spam emails should always be blocked by our automated system, and if that is not enough the Email Threat Team analyzes messages and updates the antispam pattern regularly based on source IP, domain, and content (containing URLs, text patterns, etc.).