Use the IPMAILERNAME statement to control whether this SMTP should forward non-local mail to an SMTP server on an IP network. The specified server should have network connectivity and be able to perform name resolution.
The SMTP code resolves the specified mailer name by doing an A query to the name servers (DNSs) configured in the TCPDATA data set (see NSINTERADDR statement) used by the SMTP started procedure. If no DNSs are configured, SMTP uses the local host tables to resolve the specified mailer name. SMTP does its own name resolution, normally using a UDP connection. It sends out the question (in this case an A query for the mailer's name) and interprets the name server's response. If the specified mailer name cannot be resolved, the mail is considered undeliverable.
Rule: For IPMAILERNAME, SMTP always uses a fully-qualified name for communication with the name server or for host table look-ups. Message EZA5645I in the SMTP output file, displays the fully-qualified name being used by SMTP.
For performance reasons, the location of the DNS is important to ensure timely responses to SMTP queries. The SMTP started procedure performs name resolution on every recipient even though it asks the same question to the name server. This allows the name server to change its response, and SMTP acts accordingly. However, after name resolution for the recipient is completed, SMTP uses the IP addresses associated with the recipient to send the mail.
The IPMAILERNAME statement has no defaults.
Requirement:You must specify a host name or a fully-qualified name for the SMTP mailer and an instruction indicating which mail to forward (ALL or UNKNOWN).
Parameters
- mailername
- This represents the host name or the fully-qualified name (host.domain)
of the IP mailer to which SMTP forwards the mail. If the host name
is used, then SMTP appends the domain information collected from
the TCPDATA data set (see DOMAINORIGIN statement).
If the fully-qualified name is used, the name is not modified.
Tip: A period (.) at the end of the name is considered a configuration error.
SMTP does not check the validity of this name with regards to invalid characters or misspellings. The specified mailername is limited to 80 characters; this meets the SMTPCONFG data set limit.
- ALL
- Indicates that SMTP should forward all non-local mail destined for the IP network to the specified IP mailer name.
- UNKNOWN
- Indicates that SMTP should forward only non-local mail destined for recipients on an unknown host.
Examples
IPMAILERNAME your.mailer.name ALL IPMAILERNAME
this.is.a.very.long.mailer.name...
ALL Usage notes
- IPMAILERADDRESS and MAILER... UNKNOWN provide similar functions and cannot be used when IPMAILERNAME has been coded.
- If RESOLVERUSAGE statement is coded it must be coded as RESOLVERUSAGE YES because this function requires the use of the DNS or local host tables.