postdrop Command in Linux
The postdrop command in Linux is a Postfix tool that places mail in the maildrop queue. It is used in environments where mail submission is restricted, such as when non-root users need to submit mail.
Table of Contents
Here is a comprehensive guide to the options available with the postdrop command −
Syntax of postdrop Command
The syntax of the postdrop command in Linux is as follows −
postdrop [options]
The [options] field in the above syntax is used to mention various options such as specifying the custom configuration file or enabling verbose logging.
Options of postdrop Command
The options of the postdrop command are listed below −
| Option | Description |
|---|---|
| -c config_dir | Use the specified directory for main.cf instead of the default. See MAIL_CONFIG for an alternative. |
| -r | Read messages via an internal Postfix protocol and report status on stdout. |
| -v | Enable verbose logging for debugging. Multiple -v options increase verbosity. |
How the postdrop Command Works in Linux?
The postdrop command is not invoked directly by users because it is a low-level utility designed specifically for secure mail submission in Postfix. Postfix uses it when submitting mail via sendmail. It accepts mail from postfix sendmail or other mail submission programs and drops mail into the maildrop queue (/var/spool/postfix/maildrop).
For example, send a message using the following command −
echo -e "Subject: Test Email\n\nThis is a test email." | sendmail alex@test.com
To verify that postdrop worked when sending mail through sendmail, follow the steps given below −
To check the email queue, use the following command −
mailq
Or
postqueue -p
Note the message ID, now execute the following command to check maildrop queue to verify if the message is written there −
sudo ls -l /var/spool/postfix/maildrop/
If a message appears here, postdrop has successfully written the email.
Conclusion
The postdrop command in Linux is a Postfix utility designed for secure mail submission. It places mail into the maildrop queue, ensuring restricted environments allow mail submission without direct access to Postfix's internal workings.