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The Graveyard - Products No Longer Supported => D-Link NetDefend Firewalls => Topic started by: mooniegeneral on December 02, 2012, 06:20:21 PM

Title: Firewall filtering out SMTP traffic for ONLY delegated emails
Post by: mooniegeneral on December 02, 2012, 06:20:21 PM

Sending from Gmail, you can send 'on behalf' of somebody else. I've noticed when this feature is enabled, and the firewall is set to allow and redirect port 25 to the webmail server, only this traffic bounces.

Delivery to the following recipient failed permanently:

     EMAIL@DOMAIN.com

Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the recipient domain. We recommend contacting the other email provider for further information about the cause of this error. The error that the other server returned was: 554 554 Transaction Failed: Command "FROM" field differs from data "FROM" field. (state 17).

We have a dlink NetDefend firewall (latest firmware) configured with the service SMTP over TCP

There is also SMTP-in, SMTP-inbound and SMTP-av. Perhaps this is where the problem lies, however I assume that the plain SMTP service will either allow everything or nothing, not selectively reject emails.

Title: Re: Firewall filtering out SMTP traffic for ONLY delegated emails
Post by: mooniegeneral on December 02, 2012, 06:23:30 PM

I saw this forum post which may have something to do with it

"Well well well.. after a lot of digging, we found that a rule in the firewall caused this. SMTP ALG (Application Layer Gateway) was enabled, and the rule for Anti-SPAM, 'Deny emails with mismatching SMTP command "From" address and email header "From" address' was enabled."
http://www.hmailserver.com/forum/viewtopic.php?f=7&t=17229