Malformed Envelope Senders

[irkutskoil]

Hi,

I enabled "Envelope Sender DNS Verification:" option in Mail flow policy

There is a special SMTP code for "Malformed Envelope Senders:"

But when i connect to my ESA through telnet i can stay "MAIL FROM:" header empty.

Is it OK? If yes, what is "Malformed Envelope Senders:"?

[Libin Varghese]

Hi,

An envelope sender is considered malformed if it is not RFC compliant such as missing domain information.

A blank envelope sender would not be stopped by envelope sender DNS verification as it is RFC compliant and commonly used by bounce emails generated by Microsoft exchange servers. You can certainly utilize bounce verification in order to stop illegitimate bounce emails.

http://www.cisco.com/c/en/us/support/docs/security/email-security-appliance/117918-technote-esa-00.html

Thanks
Libin Varghese