qmail: Reject unencrypted email

[Aileron79]

Hi all!

I'd like to create an email account which only accepts encrypted email. This of course shall not affect other users and their mail boxes. I don't have a problem writing a simple script which checks a single message for whether or not it's encrypted. but I have no clue where to hook such a script in a Plesk environment. Plesk obviously uses qmail as an MTA, and as spam usually is filtered at that stage I considered doing a similar thing but I don't know how, especially on a per-user-basis.

If possible I'd like to send an automated response message to unencrypted messages which contains the download link for the public key.

Alternatively I can periodically run a cronjob to check for new mail and filter accordingly, but that's not a very nice solution. I'd like to avoid usage of crond for this.

 

[Linulex]

Hello,

qmail has a very nifty system to do everything you want with an email on a per mailbox basis. It is the .qmail file located in

/var/qmail/mailnames/DOMAIN/MAILBOX/.qmail

qmail reads the .qmail file and executes the content line per line. You can place even commands in it to run external scripts if you want/need.

You will find more about it on Life With qmail site at
http://www.lifewithqmail.org/lwq.html#dot-qmail-files

Delivery of a user's mail is usually controlled by one or more ".qmail" (pronounced dot kyoo mail) files--files in the user's home directory with names beginning with .qmail. The dot-qmail man page describes .qmail file usage.

.qmail files contain a list of delivery instructions, one instruction per line. The first character of the line determines what kind of delivery is involved:
Character Delivery Type Value
# none (comment) ignored
| program command to be run by shell
/ or . mbox (if last char isn't a /) pathname of mbox (including the / or .)
/ or . maildir (if last char is a /) pathname of maildir (including the / or .)
& forward address to forward message
letter or number forward address to forward message (including the first char)

You will have to test for yourself when plesk overwrites the file. I can imagine it will get overwritten when you change something to that email via plesk, like adding a forward or so.

Hope this helps,
Jan