Start/notes.ini Parameters/SMTPGreeting

SMTPGreeting

Parameter: SMTPGreeting
Short description: Defines the greeting text (220 banner) that Domino sends on inbound SMTP connections. Set to remove hostname and version information from the banner response, denying attackers profiling of OS and Domino version. The default banner contains the server hostname plus the Domino version; with a custom value it is reduced to a neutral string.

Profile

Parameter
SMTPGreeting
Category
Mail / Router
Component
Server (outbound and inbound SMTP)
Available since
Domino 6.5 (continuously through 14.5.1)
Supported versions
9.0.1, 10.0, 11.0, 12.0, 14.0, 14.5, 14.5.1
GUI equivalent
Configuration document → NOTES.INI Settings
Possible values
Free-form string; %S = placeholder for date/time; not set = default banner with hostname + Domino version

Description

The Domino SMTP listener returns a 220 banner for every incoming TCP connection. The default banner contains the hostname as well as the Domino software version, e.g.:
220 server.example.com ESMTP Service (HCL Domino Release 14.5.1) ready at Sat, 8 May 2026 06:55:00 +0200
This information is useful to attackers because it reveals OS hints and version jumps. With SMTPGreeting, the banner is replaced with custom, neutral text:
SMTPGreeting=mail.example.com SMTP Server Ready at %S
The server then answers, for example, with:
220 mail.example.com SMTP Server Ready at Sat, 8 May 2026 06:55:00 +0200
The variable is also read by the outbound SMTP path, so it should be set on the outbound SMTP server. It works in conjunction with SMTPNOVERSIONINRCVDHDR=1, which removes the version information in the Received: headers — both are paired in HCL KB0088717 as a hardening recommendation.

Example configuration

Classic hardening (hides Domino version + hostname detail):
SMTPGreeting=mail.example.com SMTP Server Ready at %S
Neutral variant without hostname:
SMTPGreeting=ESMTP Service Ready at %S
Runtime variant (without server restart):
set config SMTPGreeting=mail.example.com SMTP Server Ready at %S
tell smtp update config

Notes & pitfalls

  • Placeholder %S: Replaced with the current date/time when the banner is sent. Without %S, the banner remains static — some spam filters and SMTP clients react more sensitively to static banners.
  • Outbound SMTP server: Per HCL KB0088717, the parameter must be set on the outbound SMTP server so that the custom banner also applies to initiated connections.
  • Combined with SMTPNOVERSIONINRCVDHDR=1: Additionally hides the Domino version in the Received: headers of outgoing mail. Together, both settings reduce information disclosure risk.
  • Activation: Takes effect after server restart or dynamically via tell smtp update config.
  • No effect on other protocols: For POP3, use POP3GREETING; for IMAP, the greeting field in the server/Internet site document; for HTTP, DominoNoBanner=1 and HTTPDisableServerHeader=1.
  • No validation: Domino does not check the banner text. An empty or syntactically incorrect banner can break SMTP connections from strict clients (e.g. RFC 5321 validators).

Sources