* Alpha release

This release has not been extensively tested, I don't recommend putting it

into production usage yet. All the IMAP4rev1 features are fully supported,

except custom message flags still need to be implemented. There's several

minor problems left, see TODO file.

* Mail storages

Maildir is the preferred storage with most robust implementation. mbox

support is available but currently it relies a little bit on good luck, I

made it mostly for personal use and I strongly recommend using maildir if

at all possible.

Maildir folders are done like with courier. INBOX is the ~/Maildir

directory, all the other folders named as ".<folder>.<subfolder>.<etc>"

under it, any directories not starting with a dot are simply ignored.

Deleting folders is made atomic by renaming them as "..<folder name>" and

deleting the directory after that. So, all directories beginning with ".."

are deleted whenever they're noticed. Indexes are stored into each folder's

root directory.

mbox storage currently requires that all mail is in user-writable

directory, eg. ~/mail. Especially using /var/mail/user is NOT supported.

You may however create a ~/mail/inbox hardlink (or symlink if not chrooted)

to pointing to /var/mail/user. All files in the mail directory are

considered as mailboxes. Directories specify subfolders in IMAP. "inbox"

file specifies the INBOX folder and can not be named otherwise. Indexes are

stored into ".imap/<mailbox name>/" directories.

imap process detects the storage from MAIL-environment which is preferred

to be in format "<storage>:<data>", for example "maildir:~/Maildir". It's

anyway allowed to be in pretty much any format as long as some of the

storages recognizes it as a valid data, so for example "MAIL=~/mail" is

first checked by maildir storage to see if it's valid maildir and

mbox storage after that.

If the MAIL environment isn't given at all, all the storages are gone

through which try to find a valid directory for themselves to use. Also as

a special case, if MAILDIR environment exists, maildir storage is used with

the directory specified in it.

Maildir storage is autodetected by checking if <directory>/cur/ exists and

we have rwx access to it. If directory isn't known, / and ~/Maildir are

checked. / is checked because we could be chrooted.

mbox storage is autodetected by checking if .imap/ (+rwx), inbox (+rw) or

mbox (+rw) exists in directory. If directory isn't known, / is tried first.

After that, ~/mail and ~/Mail directories are used if they're found without

checking if they even contain any files.

* Code

The code is split into a several libraries and binaries:

src/master - imap-master binary (see docs/design.txt)

src/login - imap-login binary

src/auth - imap-auth binary

src/imap - imap binary

src/lib - Generic library functions

src/lib-mail - RFC-822 and MIME parsering code

src/lib-imap - IMAP-specific functions for parsing, sending, etc.

src/lib-index - Mailbox indexing library, slightly IMAP-specific

src/lib-storage - Mail storage separated into interface and implementation.

imap binary uses only the interface so it's possible to

add support for any kind of mail storage (eg. SQL).

* RFCs conformed

822 - Standard for ARPA Internet Text Messages

2822 - Internet Message Format (updated rfc822)

2045..2049 - Multipurpose Internet Mail Extensions (MIME)

2060 - IMAP4rev1

2180 - IMAP4 Multi-Accessed Mailbox Practice

2595 - Using TLS with IMAP, POP3 and ACAP

2831 - Using Digest Authentication as a SASL Mechanism (DIGEST-MD5)

rfc2831

* Contact info

Timo Sirainen <tss@iki.fi>, http://dovecot.procontrol.fi/