This tool allows you to access IMAP4 server as if it were a POP3 server. It's useful when your IMAP4 server doesn't support POP3 for some reason.
The tool itself is available under GPL.
mail.jar is covered by the binary code license of Sun, not GPL.
To launch the server,
$ java -jar imap2pop.jar
Optionally, you can specify -port [port#] option to specify
a port number if you want it to use something other than the default 110.
This gateway, written in Java, behaves as a POP3 server. It reads mail from the specified IMAP4 server, as shown in the following figure.
POP3 IMAP4
Becky ---------> Gateway -----------> IMAP4 server
In a way, as you see, it works like a proxy.
To use this gateway, you need to pass "uid@imap4server[:port]" as your user id in POP3, where 'uid' is your true user id, 'imap4server' is your IMAP4 server, and optional 'port' is the port number of that server. For example, if your assigned IMAP4 server runs at "imap4.acme.com" and your user id is "kohsuke", you specify "kohsuke@imap4.acme.com" as your user id in your mailer.
The protocol gateway recognizes this format and connects to the appropriate host and port, by using the specified true user id and password.
All of the mandatory POP3 commands, as well as TOP command is (I believe) properly implemented, although some of them are terribly slow.
Specifically, UIDL, LIST, and STAT are slow especially when you have a lot of mail.
I developed this software out of necessity, when I found out that my company doesn't provide POP3 access for a reason beyond my understanding (although their server has the functionality to do so!) They told me that they don't support POP3 because it's not a standard. Heh! I couldn't believe what I heard.