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POSTDROP(1) General Commands Manual POSTDROP(1)


postdrop - Postfix mail posting utility


postdrop [-rv] [-c config_dir]


The postdrop(1) command creates a file in the maildrop directory and copies its standard input to the file.


The configuration file is in the named directory instead of the default configuration directory. See also the MAIL_CONFIG environment setting below.
Use a Postfix-internal protocol for reading the message from standard input, and for reporting status information on standard output. This is currently the only supported method.
Enable verbose logging for debugging purposes. Multiple -v options make the software increasingly verbose. As of Postfix 2.3, this option is available for the super-user only.


The command is designed to run with set-group ID privileges, so that it can write to the maildrop queue directory and so that it can connect to Postfix daemon processes.


Fatal errors: malformed input, I/O error, out of memory. Problems are logged to syslogd(8) or postlogd(8) and to the standard error stream. When the input is incomplete, or when the process receives a HUP, INT, QUIT or TERM signal, the queue file is deleted.


Directory with the file. In order to avoid exploitation of set-group ID privileges, a non-standard directory is allowed only if:
  • The name is listed in the standard file with the alternate_config_directories configuration parameter.
  • The command is invoked by the super-user.


The following parameters are especially relevant to this program. The text below provides only a parameter summary. See postconf(5) for more details including examples.

A list of non-default Postfix configuration directories that may be specified with "-c config_directory" on the command line (in the case of sendmail(1), with the "-C" option), or via the MAIL_CONFIG environment parameter.
The default location of the Postfix and configuration files.
The list of environment parameters that a privileged Postfix process will import from a non-Postfix parent process, or name=value environment overrides.
The location of the Postfix top-level queue directory.
The syslog facility of Postfix logging.
A prefix that is prepended to the process name in syslog records, so that, for example, "smtpd" becomes "prefix/smtpd".
The time limit for sending a trigger to a Postfix daemon (for example, the pickup(8) or qmgr(8) daemon).

Available in Postfix version 2.2 and later:

List of users who are authorized to submit mail with the sendmail(1) command (and with the privileged postdrop(1) helper command).

Available in Postfix version 3.6 and later:

A list of lookup tables that are searched by the UNIX login name, and that return a list of allowed envelope sender patterns separated by space or comma.
The lookup key to be used in local_login_sender_maps tables, instead of the null sender address.
The set of characters that can separate an email address localpart, user name, or a .forward file name from its extension.


/var/spool/postfix/maildrop, maildrop queue


sendmail(1), compatibility interface
postconf(5), configuration parameters
postlogd(8), Postfix logging
syslogd(8), system logging


The Secure Mailer license must be distributed with this software.


Wietse Venema
IBM T.J. Watson Research
P.O. Box 704
Yorktown Heights, NY 10598, USA
Wietse Venema
Google, Inc.
111 8th Avenue
New York, NY 10011, USA