Changing outbound SMTP port settings

Outbound SMTP port settings affect how HCL Domino® connects to other SMTP servers. Change the default port numbers and the status of the TCP/IP and TLS ports to match the settings on servers to which this server sends SMTP mail.

About this task

The outbound port settings apply to all outbound SMTP sessions. If you change an outbound port number to a nonstandard value, the server cannot establish SMTP connections with servers that listen for SMTP requests on the standard port. Similarly, if you set up the server to send SMTP over TLS only, disabling the outbound SMTP TCP/IP port, the server cannot establish SMTP connections with a remote server that accepts SMTP connections over the TCP/IP port only.

Procedure

  1. From the Domino® Administrator, click the Configuration tab and then open the Server document for the server that runs the SMTP service.
  2. Click the Ports > Internet Ports > Mailtab.
  3. In the Mail (SMTP Outbound) column, complete these fields, and then click Save & Close:
    Table 1. SMTP Outbound options

    Field

    Enter

    TCP/IP port number

    The number of the TCP/IP port on the remote server to which Domino® attempts to connect when initiating an SMTP session. The default and industry standard port for SMTP connections over TCP/IP is 25. Specify a nonstandard port only if this Domino® server makes all of its outbound SMTP connections over TCP/IP to a server that uses the nonstandard port.

    TCP/IP port status

    Choose one:

    • Enabled - The Domino® SMTP Router connects to the designated TCP/IP port number on a remote server to initiate an SMTP session. If the TLS port status is also set to Enabled, the Router attempts to use the TLS port first and uses the TCP/IP port only if it cannot connect to the TLS port.
    • Disabled (default) - The Domino® SMTP Router cannot initiate an SMTP session using the TCP/IP port on a remote server.
    • Negotiated TLS - The Domino® SMTP Router connects to the designated TCP/IP port on a remote server to initiate an SMTP session. If the remote server advertises STARTTLS during the EHLO greeting, Domino® issues a STARTTLS command to request that the remainder of the session be encrypted using TLS. If the remote server does not support STARTTLS, an unencrypted TCP/IP session ensues.

    TLS port number

    The number of the TLS port on the remote server to which Domino® attempts to connect when initiating an SMTP session. The default and industry standard port for SMTP connections over TLS is 465. Specify a nonstandard port only if this Domino® server makes all of its outbound SMTP connections over TLS to a server that uses the nonstandard port.

    TLS port status

    Choose one:

    • Enabled - The Domino® SMTP Router connects to the designated TLS port number on a remote server to initiate an SMTP session. If the Router cannot connect to the TLS port and the TCP/IP port is also enabled on both the Domino® server and the remote server, Domino® makes a second attempt to connect, using the designated TCP/IP port.
    • Disabled (default) - The Domino® SMTP Router cannot initiate SMTP sessions over the TLS port of a remote server.