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nullmailer-send(8) System Manager's Manual nullmailer-send(8)


nullmailer-send - Send queued messages




This program is responsible for coordinating the transmission of messages that have been queued by nullmailer-queue. It uses a variety of protocol modules to deliver the messages from the queue to remote "smart" servers.

When the program starts, the queue is scanned to build a list of messages to send. The queue is rescanned when either the trigger is pulled, or after pausetime seconds have elapsed after the last failed delivery. When there are no messages in the queue, nullmailer does no rescanning until the trigger is pulled. Pulling the trigger consists of opening up the trigger named pipe and writing a single byte to it, which causes this program to be awakened (if it's not already processing the queue). This procedure is done by nullmailer-queue to ensure that messages are delivered immediately. You can start delivery by hand from the command line like this:

echo 1 > trigger

Delivery of messages consists of reading the list of remote servers and then trying to deliver the messages to these servers as follows. For each remote in the list, the named protocol handler is executed once for each message remaining in the queue. If the protocol handler succeeds, the message is removed from the queue and processing continues with the next message. If the protocol handler reports a permanent failure or the message has been in the queue longer than queuelifetime, the message is moved into the failed queue and a bounce message is generated with nullmailer-dsn. If any messages remain in the queue, processing of the remaining messages continues with the next remote. When all the remotes have been tried, nullmailer-send sleeps for a number of seconds specified by pausetime before retrying sending the contents of the queue.


All the control files are reread each time the queue is run.

Sets the environment variable $HELOHOST which is used by the SMTP protocol module to set the parameter given to the HELO command. Defaults to the value of the me configuration file.
The maximum time to pause between successive queue runs, in seconds. Defaults to 24 hours (86400).
The minimum time to pause between successive queue runs when there are messages in the queue, in seconds. Defaults to 1 minute (60). Each time this timeout is reached, the timeout is doubled to a maximum of maxpause. After new messages are injected, the timeout is reset. If this is set to 0, nullmailer-send will exit immediately after going through the queue once (one-shot mode).
The maximum time a message is allowed to live in the queue before being considered permanently failed, in seconds. Defaults to 7 days (604800).
This file contains a list of remote servers to which to send each message. Each line of this file contains a remote host name or address followed by an optional protocol string, separated by white space. The protocol name defaults to smtp, and may be followed by additional options for that module. See the "PROTOCOL OPTIONS" section for a list of the available options. The options may optionally be prefixed by -- but this is not required. The line is parsed according to standard shell quoting rules. For example, to connect to port 2525 on your SMTP smart host, which also requires SMTP authentication, and initiate TLS with STARTTLS, use:

smarthost.dom smtp port=2525 starttls user=user pass='my pass phrase'

Blank lines and lines starting with a pound (#) are ignored.

The time to wait for a remote module listed above to complete sending a message before killing it and trying again, in seconds. Defaults to 1 hour (3600). If this is set to 0, nullmailer-send will wait forever for messages to complete sending.


Set an alternate port number to connect to on the remote host. For example, SMTP may use port=587 for the alternate SMTP "submission" port.
Set the SMTP authentication user name.
Set the SMTP authentication password.
Set the source address for connections to the remote host.
Force SMTP "AUTH LOGIN" mode instead of auto-detecting.
Connect using TLS. This will automatically switch the default port to 465.
Alias for the tls option for compatibility.
Use the STARTTLS command to initiate a TLS session.
Set the filename for a TLS client certificate to send to the server.
Set the filename for the private key for a TLS client certificate. Defaults to the same file name as x509certfile.
Set the TLS certificate authority trust filename. Defaults to /etc/ssl/certs/ca-certificates.crt.
Set the TLS certificate revocation list filename.
Specify that TLS X.509 files above are in DER format instead of PEM.
Don't abort a TLS connection if the server certificate fails validation. Use this only if you know the server uses an invalid certificate.
Use TLS anonymous authentication - replacing certificate authentication. This means no external certificates or passwords are needed to set up the connection. With this option your connection is vulnerable to man-in-the-middle (active or redirection) attacks. However, the data are integrity protected and encrypted from passive eavesdroppers. This option must be used with the insecure option - to acknowledge that you know what you are doing.


The failed message queue.
The outgoing message queue.
A trigger file to cause immediate delivery.
The configuration directory.
The protocol program directory.


nullmailer-smtp(8), nullmailer-qmqp(8) nullmailer-dsn(1), nullmailer-inject(1), nullmailer-queue(8), mailq(1) on how to setup a certificate-less Postfix SMTP server