I doubt you would get much help from the courier developers. They think
there is no room for extremely useful backward compability with slightly
older than new email clients. Instead they wish to force upon the world,
the use of new esmtp clients which barely work correctly with esmtp. If
Complete nonsense. Outlook Express is a "new" esmtp client?
Netscape/Mozilla is a "new" esmtp client? Eudora is a "new" esmtp client?
Mulberry is a "new" esmtp client?
happen under the current management of courier. So you best bet is (if
its not too late) move to Qmail, and only use courier as IMAP secondary
Really? Qmail's POP3 server supports POP-before-SMTP?
Authenticated SMTP is now supported by every mail client worth mentioning.
The time for POP-before-SMTP hacks is long gone.