How does the server periodically delete messages from the inbox?

Hello.

For example, I now have 13 users, and there are three scenarios:

1. Emails from 5 users will be retained for the last 60 days.
2. Emails from 2 users will be retained for the last 30 days.
3. Emails from 6 users will be retained for the last 7 days.

Thank you.

 

I did use POP3 and enable the retention option.
What do you recommend for this external software?
They know the time of the reservation, have communicated and decided in advance ...

Thank you.

 

wouldn't it be enough to have the virtual_transport = dovecot-lmtp configured using sieve plugin and
use a sieve per user like this

Code:

require ["fileinto", "envelope", "imap4flags", "copy"];

# If the email is sent by the user, file it into the Sent folder
if address :matches ["from"] "[email protected]" {
    fileinto :copy "Sent";
    stop;
}

# Otherwise, file it into the Inbox
fileinto :copy "Inbox_imap";

and use a milter for postfix like

Code:

import Milter
import os

class SaveSentMilter(Milter.Base):
    def __init__(self):
        self.id = Milter.uniqueID()
        self.from_address = None
        self.to_addresses = []
        self.email_content = []

    def envfrom(self, mailfrom, *str):
        self.from_address = mailfrom
        return Milter.CONTINUE

    def envrcpt(self, to, *str):
        self.to_addresses.append(to)
        return Milter.CONTINUE

    def header(self, name, value):
        self.email_content.append(f"{name}: {value}\n")
        return Milter.CONTINUE

    def eoh(self):
        self.email_content.append("\n")
        return Milter.CONTINUE

    def body(self, chunk):
        self.email_content.append(chunk)
        return Milter.CONTINUE

    def eom(self):
        email_content_str = ''.join(self.email_content)   

        # Save email to Sent folder
        self.save_to_sent_folder(email_content_str)

        return Milter.CONTINUE

    def save_to_sent_folder(self, email_content):
        # Prepare the Dovecot delivery command
        delivery_command = f"/usr/lib/dovecot/dovecot-lda -d {self.from_address} -m 'Sent'"
   
        # Use a pipe to send the email to Dovecot LDA
        process = os.popen(delivery_command, 'w')
        process.write(email_content)
        process.close()

def main():
    Milter.factory = SaveSentMilter
    Milter.runmilter("save_sent_milter", "/var/spool/postfix/milter/save_sent_milter.sock", 5)

if __name__ == "__main__":
    main()

did not test the code, it's just a reference to think of how it might be done.

Pop3 and Imap may use the same INBOX folder or not, you can change the namespace inbox
to have a different folder for inbox = yes or special_use = \Sent

Now I think about it, yeah this can get a little more complex. But in theory this would probably
be a way to go, just with a little bit more thinking, time and effort. Not sure if there is a ready made solution.

There could be a milter for incoming and outcoming only, thus one could do two milters with different actions, probably could be done more elegant too.

Pop3-Clients do not access the folders thus only thing what's left would be to setup a cronjob or something
to check on the files age and make "the purge"

edit: rethinking... using sieve for imap would be bad, just use the milter approach and leave a clean sieve for users