POP3 - courier - force leave copy on the server (gmail like)

[spector]

Is there any way to force leaving copy of email on the server with pop3 and courier-mta? Gmail has this option. It would be usefull as accidential download&delete often happens with pop3 access, especialy if multiple persons use it.

[sirdopes]

Why not use imap instead? This is what it is designed for.

[garrettp]

+1 for IMAP. The POP3 protocol was not designed for this type of functionality and that's exactly where IMAP shines. IMAP is also much more user-friendly when it comes to managing folders as well.

[spector]

Offtopic. Thread is for ppl with serious knowledge about courier-mta or perhaps other replacement for pop3.

[garrettp]

Being familiar with the POP3 protocol, I'm sure you realize this is something that is very difficult to enforce. Most modern clients and server daemons, including both Courier and Dovecot, support the UIDL command necessary to allow POP3 to store messages on the server, but this in-and-of itself does not provide a method of enforcing storage. Standards-compliant POP3 email clients will send a RETR command followed by a DELE command to the server to mark a message for removal. For a server to force storage of messages via POP3 it would either have to ignore DELE commands (as Gmail's appear to have been programmed to do) or remove the standard of POP3 that removes all messages marked using DELE when a QUIT is received from the client.

Both of these are going to require some significant changes to the POP3 daemon, both of which are outside of the scope of cPanel's support.

The easier and supported route would be to ask all of your users to enable the "Leave a copy of messages on the server" option, or disable POP3 altogether and force the use of IMAP.