Release 1.07-PRE-4 of IMAP-IDLE, a plugin that provides "push-mail" support for Apple's email client, is available for download.

This version asks Mail to sync, rather than simply check for new mail, and listens to additional types of notifications from the IMAP server. The result is that your IMAP mailbox stays in sync with the server better. This version also determines IDLE capability by trying to use it, rather than by depending on the server reporting IDLE support in its CAPABILITY response (as it turns out, some servers don't have accurate CAPABILITY responses). It supports SSL and clear-text connections (for security reasons, please avoid non-encrypted IMAP sessions).

It does not support TLS, Kerberos or NTLM. Be aware that Pair.com's IMAP servers advertise IDLE support and even accept IDLE mode requests, but never actually send notifications, making IMAP-IDLE useless.

UPDATE
I uploaded a new build, which reports itself as "IMAP-IDLE Version 1.07-PRE-4b (2007-09-01)" in the console log. If you downloaded your version before 2:10pm Eastern time on Sept 1, 2007 -- download it again. You can also quit and re-launch Mail, and look for "IMAP-IDLE Version 1.07-PRE-4b (2007-09-01)" in the console log, to be sure you've got the right version.