Purpose

Use the HELO command to identify the domain name of the sending host to SMTP before a MAIL FROM command.

Parameters

domain_name

Specifies the domain name of the sending host.

Usage

• The HELO command is sent once before a MAIL FROM command.
• If domain_name is not known, you can send messages, but the message never heard of you is returned. This message indicates that the HELO command is accepted, but that the host name could not be resolved either through the name server or through the host tables.
• HELO commands received over a TCP connection that has a domain_name IP address that does not match the IP address of the ForeignSocket field of the connection information record are accepted. However, the reply text indicates the mismatch. HELO commands received over a batch SMTP connection with a domain_name that does not match the host name of the origination point of the spool data set are accepted, but the reply text indicates the mismatch.