Hello,

We have quite a few aliases that have a mix of local user accounts plus remote accounts in the same alias.

Example - ali...@myserver.com will have: loca...@myserver.com loca...@myserver.com remo...@otherserver.com remo...@otherserver.com

Recently, there's been an issue with users on a specific remote server which was traced to their spam software.

The spam software will reject emails with an empty sender when the email is destined to more than 3 people.

A tcpflow of the transaction from courier to their server shows:

RSET MAIL FROM:<> RCPT TO:<remo...@otherserver.com> RCPT TO:<remo...@otherserver.com> RCPT TO:<remo...@otherserver.com> RCPT TO:<remo...@otherserver.com> DATA Received: <snipped> To: ali...@myserver.com From: User <us...@myserver.com> Subject: Distribution Test - Please Disregard

This is a test. Please disregard.

. RSET

The first 3 remote users will be accepted but the system will reject the last because the MAIL FROM is being sent empty.

This has only been an issue recently with this specific server.

The spam software is absolutely causing the rejects. But it's doing so because of the empty MAIL FROM.

Is courier correct in sending the empty MAIL FROM or am I missing a setting? Or is the spam software misbehaving?

Courier version is 0.52.1.

Thanks,

Rob