This seems to be working fine when the user is not allowed to receive messages based on the class of service added to block inbound mail like this, I also see the same thing when the user below is in a group and i add the group in the membership list.

When testing this with 2 GW systems I see the following undeliverable in the senders mailbox, it reports the 551 not 550 as the user is not unknown but blocked.

Sending GWIA log shows

08:57:45 DEA7 DMN: MSG 4833 SMTP session ended: [10.94.75.202] (mxtrunk.robvk.com)
08:57:54 E2D2 MSG 4833 Analyzing result file: /gwise/maindom/wpgate/gwia/result/r7af0588.011
08:57:54 E2D2 MSG 4833 Command: trunk.robvk.com
08:57:54 E2D2 MSG 4833 Response: 220 trunk.robvk.com Ready
08:57:54 E2D2 MSG 4833 Command: EHLO gwmain.robvk.com
08:57:54 E2D2 MSG 4833 Response: 250 ok
08:57:54 E2D2 MSG 4833 Command: MAIL FROM:<rvkooten@robvk.com>
08:57:54 E2D2 MSG 4833 Response: 250 Ok
08:57:54 E2D2 MSG 4833 Detected error on SMTP command
08:57:54 E2D2 MSG 4833 Command: RCPT TO:<avkooten@trunk.robvk.com>
08:57:54 E2D2 MSG 4833 Response: 551 Forwarding to remote hosts disabled
08:57:54 E2D2 MSG 4833 Command: DATA
08:57:54 E2D2 MSG 4833 Response: 221 trunk.robvk.com Closing transmission channel
08:57:54 E2D2 Building undeliverable message
08:57:54 E2D2 MSG 4833 File: /gwise/maindom/wpgate/gwia/wpcsin/4/47af0592.i25 Message Id: (67AEF782.169:106:361) Size: 2.4 Kb

Receiving GWIA logs shows

08:58:07 B88F DMN: MSG 216 Accepted connection: [10.94.73.182] ()
08:58:07 B88F DMN: MSG 216 SMTP upgraded to a secure connection.
08:58:07 B88F DMN: MSG 216 Receiving file: /gwise/trunkdom/wpgate/gwia/receive/f950fa76.001
08:58:07 B88F DMN: MSG 216 Recipient rejected: avkooten@trunk.robvk.com (4)
08:58:07 B88F DMN: MSG 216 QUIT command with unfinished file
08:58:07 B88F DMN: MSG 216 Received file discarded: /gwise/trunkdom/wpgate/gwia/receive/f950fa76.001
08:58:07 B88F DMN: MSG 216 SMTP session ended: [10.94.73.182] ()

Whats is it exactly you configured, is there another host involved as you see above this receiving GWIA does report the right status back to the sending server

Hello,

Yes, you're right there is an smtp proxy involved that bounced the message:

2025-02-14 10:38:15 H=192.168.0.15 [192.168.0.15] SMTP error from remote mail server after RCPT TO:<abcde@efgh.com>: 551 Forwarding to remote hosts disabled
2025-02-14 10:38:15 abcde@efgh.com P=<pqrst@zzz.com> R=static_route_hostlist T=static_smtp H=192.168.0.15 [192.168.0.15]:25 X=TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256 CV=no: SMTP error from remote mail server after RCPT TO:<abcde@efgh.com>: 551 Forwarding to remote hosts disabled

And this does not trigger any error message to the sender.

Thanks.

Sylvain

Time to replace that smtp proxy, it's not up to modern standards in any way. It aparently accepts the whole incoming mail before it checks if it can deliver it (store and forward). This is unuseable these days.

Hi,

The smtp proxy is the firewall that (hopefully) does all filtering and anti-virus/spam/phishing tasks.

Thanks

Sylvain

Mabye. Still the way it works now is not acceptable nor useable any more. It maybe misconfigured, or it's a product that's not up to the task.