Actually, you can do virtual users without shell accounts via courier as well. I'm running a Postfix/amavisd/spamassassin MTA with courier IMAP/SASL/Mysql All users are virtual and administrered via the Postfix admin PHP app. There are heaps of tutorials around on how to do this, like:http://www.webconexion.net/knowledgebase/linux_howto/virtual_mail_server.php http://postfixwiki.org/index.php?title=Virtual_Users_and_Domains_with_Courier-IMAP_and_MySQLhttp://www.gentoo.org/doc/en/virt-mail-howto.xml
I used the howto from http://high5.net/howto/ and their postfix admin tool and have had great success with it.
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