Enabling Premium antispam stops mail flow and you instead get the error 421 ... SMTP service not available, closing transmission channel

Products

• Mail Security for Domino

Issue/Introduction

When Premium Antispam in enabled, mail stops flowing.

If you try to connect via telnet to the SMTP server you get the error message: "421 ... SMTP service not available, closing transmission channel"

Cause

In the Domino server Basic Configuration Document you had enable the option "Load Internet configurations from Server/Internet Sites documents".

When the option "Load Internet configurations from Server/Internet Sites documents" is enabled, Domino creates a new SMTP Inbound Sites document in Web/Internet Sites. This document is created based on the current configuration of the "notes/internet port" document (by default port 25), and is being used by the Domino server.

When you enable Premium Antispam, nnpas runs a script to set Domino to listen on a random high numbered port and starts listening to port 25. This change is done to the server document and is not reflected in the new SMTP Inbound Site document.

Resolution

Once the Premium Antispam is enabled, delete and recreate the SMTP Inbound Site document. This can be found in the Web section in the left-hand column under the Configuration tab of your Domino Administrator. When Web is selected, you can then edit your Internet Sites. Once it is deleted and recreated, it will use the new port that SMS for Domino has configured in the server ports configuration document. You may need to shutdown and restart Domino for the changes to take effect.

Be sure your SMTP Inbound Site Document looks like the following with your environmental details: