Courier-IMAP

Courier-IMAP is a fast, scalable, enterprise IMAP server that uses Maildirs. Many E-mail service providers use Courier-IMAP to easy handle hundreds of thousands of mail accounts.

With the built-in IMAP and POP3 aggregation proxy in Courier-IMAP 4.0, the only practical limit to Courier's horizontal scalability is available LAN bandwidth. In proxy mode, a pool of Courier servers receive IMAP and POP3 connections from clients, wait for the clients to send a login request, look up the mail account's server, and establish a proxy connection to the actual server that hosts the mail account.

Please note that this IMAP server does NOT handle traditional mailbox files (/var/spool/mail, and derivatives), it was written and optimized for the specific purpose of providing IMAP access to Maildirs.

"Maildir" is a directory-based mail storage format originally introduced in the Qmail mail server, and adopted as an alternative mail storage format by both Exim and Postfix. Courier-IMAP is popular on Qmail/Exim/Postfix sites that are configured to use maildirs. The primary advantage of maildirs is that multiple applications can access the same Maildir simultaneously without requiring any kind of locking whatsoever. Maildir is a faster and more efficient way to store mail. It works particularly well over NFS, which has a long history of locking-related woes.

This is the same IMAP server that's included in the Courier mail server, but configured as a standalone IMAP server that can be used with other mail servers - such as Qmail, Exim, or Postfix - that deliver to maildirs. A Courier/Postfix combination is very popular. If you already have Courier installed, you do not need to download this version. If you install this version, you must remove it if you later install the entire Courier server. It's possible to have both versions installed, but this will require a delicate juggling act that you'll have to learn on your own.

What is new in this release:

• Makefile.am (imapd.cnf): Compatibility fixes.
• maildir/maildirwatch.c (maildirwatch_alloc): Use alarm() to kill the process if FAMOpen() takes more than 15 seconds to return. Should prevent a hung process if FAM/Gamin is fubared.
• pop3dserver.c: Make printed() and putchar() macros.
• imapd.cnf pop3d.cnf (default_md): added default_md = sha1
• rfc822/rfc822.c (rfc822_print_common_nameaddr): Prevent segfault if address decode fails.
• Fix make check failure when libidn is not available.
• Rebuilt man pages with updated stylesheets.

What is new in version 4.8.0:

• tcpd/configure.in: Check if explicit linking with libgpg-error is required.
• imapd.c (main): Fix typo in alert message.
• Big quota patch (with some changes).
• imapd.c (main): Dummy FAM/Gamin initialization, report an error during login, upon a failure.
• imapd.c (imapenhancedidle): Make FAM error more meaningful.
• pop3dserver.c (main): "disableinsecurepop3" account option disables non-SSL logins.
• imapd.c (chkdisabled): "disableinsecureimap" account option disables non-SSL logins.

What is new in version 4.7.0:

• 2009-11-22 Sam Varshavchik rfc822/rfc822.c: Removed rfc822_praddr().rfc822/rfc822_getaddr.c (rfc822_getaddr): Implement rfc822_getaddr()by calling rfc822_display_addr_tobuf(), instead of rfc822_praddr().rfc822/testsuite.c (doaddr): Remove rfc822_addrlist() andrfc822_namelist().2009-11-21 Sam Varshavchik msgenvelope.c (doenva): Replace rfc822_getname() byrfc822_display_name_tobuf() with a NULL character set.rfc822/rfc822_getaddr.c: Remove rfc822_prname() andrfc822_prname_orlist(), replaced by rfc822_display_name() with a NULLcharacter set.rfc822/rfc2047u.c (rfc822_display_name): Semantical change --without an explicit name, display the address as the name. If therequested character set is NULL, do not decode RFC2047-encoded content,return it as is.2009-11-17 Sam Varshavchik rfc2045/rfc2045reply.c (mkreply): Fix logic for locating thename used for salutation.rfc822/rfc2047u.c (rfc2047_print_unicodeaddr): Fix several formattingissues with deprecated RFC 822 distribution lists: spurious commaadter the last address, pass the space after the ':' as a separatorcharacter.rfc822/rfc2047.c (counts2/save): Fix line-wrapping of encodedaddresses.rfc822/rfc2047u.c (rfc822_display_addr_tobuf): New function.2009-11-14 Sam Varshavchik rfc822/rfc822.c (rfc822_print_common): Rewrite.rfc822/rfc2047u.c (rfc822_display_name_int): Fixed various rules forencoding names to be more MIME compliant.(rfc822_display_addr_str): Renamed from rfc822_display_addr(), for aconsistent API.(rfc822_display_addr): New function, decode the wire format of a singleaddress. Names are MIME decoded, addresses are IDN-decoded.(rfc2047_print_unicodeaddr): Do not output a dummy name for anaddress without one.(rfc822_display_addr_str_tobuf): New function, version ofrfc822_display_addr_str() that collects the output into a buffer.rfc822/rfc2047.c (rfc822_encode_domain): New function -- IDN-encodea domain, with an optional "user@".(rfc2047_encode_header_addr): Renamed rfc2047_encode_header(), for aconsistent API.(rfc2047_encode_header_tobuf): New function, encode a header fromdisplayed format to wire format. Names are encoded using RFC 2047,addresses using IDN.2009-11-08 Sam Varshavchik rfc822/rfc2047.h: Expose raw RFC 2047 decoding function,rfc2047_decoder().rfc822/rfc822hdr.c (rfc822hdr_is_addr): New function.rfc822/rfc822.c (tokenize): Tweak the logic for collecting RFC 2047atoms.rfc822/rfc2047u.c (rfc822_display_name): New function,replaces rfc2047_print().(rfc822_display_name_tobuf): New function,replaces rfc2047_print().(rfc822_display_namelist): New function,replaces rfc822_namelist().(rfc822_display_addr): New function, replaces rfc2047_print().(rfc2047_print_unicodeaddr): Renamed from rfc2047_print_unicode().(rfc822_display_hdrvalue): New function, replaces rfc2047_decode(),rfc2047_decode_simple(), rfc2047_decode_enhanced().(rfc822_display_hdrvalue_tobuf): New function, ditto.rfc822/rfc2047.c: Removed rfc2047_decode(), rfc2047_decode_simple(),rfc2047_decode_enhanced(), rfc2047_print().rfc822/Makefile.am: Link against GNU IDN library.thread.c (thread_ref_callback): SUBJECT for THREAD REFERENCES wasn'tgetting converted to UTF-8 at the right point, moved it up intosearch.csearch.c (fill_search_header): SUBJECT search key was beingMIME-decoded twice.

What is new in version 4.5.0:

• Log more fatal errors on stderr
• GnuTLS: add support for chained certs
• Completely empty MIME entities incorrectly match any SEARCH request.
• Some performance optimizations in header parsing
• Incorrect reference to POP3_STLS in po3pdserver.c - should be POP3_TLS.