How to Run a script when a mail arrives in mail server? (Debian)

Question

I want to parse and insert some information from the mail that just arrived in a mission critical application's mail server.

I there any way to configure my mail server so that it run a script when mail arrives.

Although I have a debian system but any generic solution (Linux) will do.

Answer 1

Looks like someone else has already answered this but thought I'd put down a specific answer for you.

I would use procmail and use a recipe in your .procmailrc similar to this:

#turn this off when you're finished testing :)
VERBOSE=on
LOGFILE=/home/user/procmail.log

:0 c #the c means continue on after this recipe is parsed
| /path/to/your/script

You'll also need a default recipe at the bottom to direct the mail into your maildir.

Answer 2

In postfix you could hold all incoming messages (that matches some pattern, or simply all of them), have your application pick them up in the hold/ directory and then place them back to the incoming/ directory once done. This is how the antispam filter MailScanner works when used with postfix.

In the Postfix configuration file /etc/postfix/main.cf add this line:
header_checks = regexp:/etc/postfix/header_checks
In the file /etc/postfix/header_checks add this line:
/^Received:/ HOLD

The effect of this is to tell Postfix to move all messages to the HOLD queue, when your application is done I believe you should put the mails in the incoming/ directory.

Answer 3

Here's a good howto on incoming mail processing. The simplese thing to do is to use the .forward mechanism as described, to pipe a message through a script. Create a mode 600 .forward file in the user's home directory and put a pipe to a script in it:

"|$HOME/bin/your.program -and some arguments" 

However, you should look at using procmail instead, as that howto details. Procmail gives you a lot of advantages, such as more sophisticated logging and mail processing. Here's a simple .procmailrc example (again from that same howto):

:0
* !^FROM_DAEMON
* !^FROM_MAILER
* !^X-Loop: myaddress@myhost.mydomain.org
| $HOME/bin/my.script 

which has some nice features, like the ability to detect and stop mail loops.