etrn(1M) System Administration Commands etrn(1M)NAMEetrn - start mail queue run
SYNOPSISetrn [-b] [-v] server-host [client-hosts]
DESCRIPTION
SMTP's ETRN command allows an SMTP client and server to interact, giv‐
ing the server an opportunity to start the processing of its queues for
messages to go to a given host. This is meant to be used in start-up
conditions, as well as for mail nodes that have transient connections
to their service providers.
The etrn utility initiates an SMTP session with the host server-host
and sends one or more ETRN commands as follows: If no client-hosts are
specified, etrn looks up every host name for which sendmail(1M) accepts
email and, for each name, sends an ETRN command with that name as the
argument. If any client-hosts are specified, etrn uses each of these as
arguments for successive ETRN commands.
OPTIONS
The following options are supported:
-b System boot special case. Make sure localhost is
accepting SMTP connections before initiating the SMTP
session with server-host.
This option is useful because it prevents race condi‐
tions between sendmail(1M) accepting connections and
server-host attempting to deliver queued mail. This
check is performed automatically if no client-hosts are
specified.
-v The normal mode of operation for etrn is to do all of
its work silently. The -v option makes it verbose,
which causes etrn to display its conversations with the
remote SMTP server.
ENVIRONMENT VARIABLES
No environment variables are used. However, at system start-up,
svc:/network/smtp:sendmail reads /etc/default/sendmail. In this file,
if the variable ETRN_HOSTS is set, svc:/network/smtp:sendmail parses
this variable and invokes etrn appropriately. ETRN_HOSTS should be of
the form:
"s1:c1.1,c1.2 s2:c2.1 s3:c3.1,c3.2,c3.3"
That is, white-space separated groups of server:client where client can
be one or more comma-separated names. The :client part is optional.
server is the name of the server to prod; a mail queue run is requested
for each client name. This is comparable to running:
/usr/lib/sendmail -qR client
on the host server.
EXAMPLES
Example 1: Using etrn
Inserting the line:
ETRN_HOSTS="s1.domain.com:clnt.domain.com s2.domain.com:clnt.domain.com"
in /etc/default/sendmail results in svc:/network/smtp:sendmail invoking
etrn such that ETRN commands are sent to both s1.domain.com and
s2.domain.com, with both having clnt.domain.com as the ETRN argument.
The line:
ETRN_HOSTS="server.domain.com:client1.domain.com,client2.domain.com"
results in two ETRN commands being sent to server.domain.com, one with
the argument client1.domain.com, the other with the argument
client2.domain.com.
The line:
ETRN_HOSTS="server1.domain.com server2.domain.com"
results in set of a ETRN commands being sent to both server1.domain.com
and server2.domain.com; each set contains one ETRN command for each
host name for which sendmail(1M) accepts email, with that host name as
the argument.
FILES
/etc/mail/sendmail.cf sendmail configuration file
/etc/default/sendmail Variables used by svc:/net‐
work/smtp:sendmail
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │SUNWsndmu │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Stable │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOsendmail(1M), attributes(5)
RFC 1985
NOTES
Not all SMTP servers support ETRN.
SunOS 5.10 10 Aug 2004 etrn(1M)
