IMAP2POP was developped to add IMAP support to a bad mail client which only supported POP3. After upgrading to a much better mail client IMAP2POP is not longer developped actively. But it runs very stable, might be useful in many cases and comes with a lot of features:
Add IMAP support for POP3-only mail clients
The main idea: A program without IMAP support should be able to receive e-mails of IMAP accounts. IMAP2POP is a helper which acts as client connecting to the real IMAP server and as server communicating with your mail client.
Some mail clients display IMAP boxes very uncomfortable (differs from coverage to coverage). By emulating POP3 accounts all mails can be shown much clearer.
Some mail providers (like web.de) forbid common using POP3 accounts to reduce server load. That is very annoying if you are waiting for an urgent mail. IMAP2POP is able to breake this limitation.
Receive other POP3 servers' mails (POP3-Relay)
An additional option: You can use IMAP2POP to forward POP3 traffic. This might be very useful when emulating virtual boxes for some users or to avoid error messages (see below).
Poll different accounts on different servers
Of course IMAP2POP might be used for serveral servers. IMAP2POP uses an internal database to decide which user owns which mails. After filling its user tables you can use two (or more) IMAP boxes in one mail client.
Avoid raising of annoying error messages
If you have a bad wireless connection or a non-permanent Internet access you know the problem of nice error dialogs. IMAP2POP is able to ease those by ignoring errors (your mail client sees an empty box) or by sending beautiful error mails to inform you. Of course you can disable this features! In this circumstances your mail client will display everthing like it did before.
Default user rules that ease user table configuration
Not anyone needs different mail forwards. To ease configuration you might train IMAP2POP to one account that will be uses by default. But others might be configures too - so it is possible to map your users to a default mail server but some of them to another box (a features for heavy installations).
IMAP2POP should learn another very important POP3 command that is used by several mail clients. After that IMAP2POP would supported the full scope of operation of POP3. Furthermore IMAP2POP will be translated into English (but as you can see, my Englisch is bad) to expand audience of IMAP2POP.
IMAP2POP is published under GPL and might be downloaded at its project site on SourceForge.net.