Difference between revisions of "OfflineIMAP"

Revision as of 04:07, 3 January 2013

OfflineIMAP is a Python utility to sync mail from IMAP servers. It does not work with the POP3 protocol or mbox, and is usually paired with a MUA such as Mutt.

Installing

Install the offlineimap package with pacman:

# pacman -S offlineimap

Configuring

Offlineimap is distributed with two default configuration files, which are both located in /usr/share/offlineimap/. offlineimap.conf contains every setting and is thorougly documented. Alternatively, offlineimap.conf.minimal is not commented and only contains a small number of settings (see: Minimal).

Copy one of the default configuration files to ~/.offlineimaprc.

Minimal

The following file is a commented version of offlineimap.conf.minimal.

~/.offlineimaprc

[general]
# List of accounts to be synced, separated by a comma.
accounts = main

[Account main]
# Identifier for the local repository; e.g. the maildir to be synced via IMAP.
localrepository = main-local
# Identifier for the remote repository; i.e. the actual IMAP, usually non-local.
remoterepository = main-remote
# Status cache. Default is plain, which eventually becomes huge and slow.
status_backend = sqlite

[Repository main-local]
# Currently, offlineimap only supports maildir and IMAP for local repositories.
type = Maildir
# Where should the mail be placed?
localfolders = ~/Maildir

[Repository main-remote]
# Remote repos can be IMAP or Gmail, the latter being a preconfigured IMAP.
type = IMAP
remotehost = host.domain.tld
remoteuser = username

Usage

Before running offlineimap, create any parent directories that were allocated to local repositories:

$ mkdir ~/Maildir

Now, run the program:

$ offlineimap

Mail accounts will now be synced. If anything goes wrong, take a closer look at the error messages. OfflineIMAP is usually very verbose about problems; partly because the developers didn't bother with taking away tracebacks from the final product.

Miscellaneous

Various settings and improvements

Running offlineimap in the background

Most other mail transfer agents assume that the user will be using the tool as a daemon by making the program sync periodically by default. In offlineimap, there are a few settings that control backgrounded tasks.

Confusingly, they are spread thin all-over the configuration file:

~/.offlineimaprc

# In the general section
[general]
# Controls how many accounts may be synced simultaneously
maxsyncaccounts = 1

# In the account identifier
[Account main]
# Minutes between syncs
autorefresh = 5
# Number of quick-syncs between autorefreshes. Quick-syncs do not update if the
# only changes were to IMAP flags
quick = 10

# In the remote repository identifier
[Repository main-remote]
# Instead of closing the connection once a sync is complete, offlineimap will
# send empty data to the server to hold the connection open. A value of 60
# attempts to hold the connection for a minute between syncs (both quick and
# autorefresh).This setting has no effect if autorefresh and holdconnectionopen
# are not both set.
keepalive = 60
# OfflineIMAP normally closes IMAP server connections between refreshes if
# the global option autorefresh is specified.  If you wish it to keep the
# connection open, set this to true. This setting has no effect if autorefresh
is not set.
holdconnectionopen = yes

systemd Service

Writing a systemd service for offlineimap is trivial, just be sure to run it as the correct user by replacing the User=UserToRunAs with your user. (e.g. User=wgiokas)

offlineimap-user.service

[Unit]
Description=Start offlineimap as a daemon
Requires=network.target
After=network.target

[Service]
User=UserToRunAs
ExecStart=/usr/bin/offlineimap

[Install]
WantedBy=multi-user.target

cron job

1. Configure background jobs as shown in #Running offlineimap in the background.

2. Use a log-friendly user interface:

~/.offlineimaprc

[general]
# This will suppress anything but errors
ui = quiet

3. Write a wrapper script for daemonizing programs, or use the one shown below:

/usr/local/bin/start_daemon

#!/bin/sh

set -efu

ionice_class=
ionice_priority=
nice=

while getopts c:p:n: f; do
	case $f in
	c) ionice_class=$OPTARG;;
	p) ionice_priority=$OPTARG;;
	n) nice=$OPTARG;;
	*) exit 2;;
	esac
done
shift $((OPTIND - 1))

cmd=$*
io=

if pgrep -u "$(id -u)" -xf -- "$cmd" >/dev/null 2>&1; then
	exit 0
fi

if type ionice >/dev/null 2>&1; then
	[ -n "$ionice_class" ]    && { io=1; cmd="-c $ionice_class $cmd"; }
	[ -n "$ionice_priority" ] && { io=1; cmd="-n $ionice_priority $cmd"; }
	[ -n "$io" ] && cmd="ionice $cmd"
fi

if type nice >/dev/null 2>&1; then
	[ -n "$nice" ] && cmd="nice -n $nice $cmd"
fi

exec $cmd

4. Finally, add a crontab entry:

$ crontab -e

The line should specify the interpreter for correct pgrep -xf results:

*/5 * * * * exec /usr/local/bin/start_daemon -n19 -c2 -p7 python2 /usr/bin/offlineimap

The wrapper script is needed because offlineimap has the tendency to sporadically crash, even more so when facing connection problems.

Automatic mutt mailbox generation

Mutt cannot be simply pointed to an IMAP or maildir directory and be expected to guess which subdirectories happen to be the mailboxes, yet offlineimap can generate a muttrc fragment containing the mailboxes that it syncs.

~/.offlineimaprc

[mbnames]
enabled = yes
filename = ~/.mutt/mailboxes
header = "mailboxes "
peritem = "+%(accountname)s/%(foldername)s"
sep = " "
footer = "\n"

Then add source ~/.mutt/mailboxes to ~/.mutt/muttrc.

Gmail configuration

This remote repository is configured specifically for Gmail support, substituting folder names in uppercase for lowercase, among other small additions. Keep in mind that this configuration does not sync the All Mail folder, since it is usually unnecessary and skipping it prevents bandwidth costs:

~/.offlineimaprc

[Repository gmail-remote]
type = Gmail
remoteuser = user@gmail.com
remotepass = password
nametrans = lambda foldername: re.sub ('^\[gmail\]', 'bak',
                               re.sub ('sent_mail', 'sent',
                               re.sub ('starred', 'flagged',
                               re.sub (' ', '_', foldername.lower()))))
folderfilter = lambda foldername: foldername not in '[Gmail]/All Mail'
# Necessary as of OfflineIMAP 6.5.4
sslcacertfile = /etc/ssl/certs/ca-certificates.crt

Not having to enter the password all the time

.netrc

Add the following lines to your ~/.netrc:

   machine hostname.tld
   login [your username]
   password [your password]

Don't forget to give the file appropriate rights like 600 or 700:

  chmod 600 ~/.netrc

Gnome Keyring

http://www.clasohm.com/blog/one-entry?entry_id=90957 gives an example of how to use gnome-keyring to store the password.

python-keyring

There's a general solution that should work for any keyring. Install python-keyring from AUR, then change your ~/.offlineimaprc to say something like:

[general]
pythonfile = /home/user/offlineimap.py
…
[Repository RemoteEmail]
remoteuser = username@host.net
remotepasseval = keyring.get_password("offlineimap","username@host.net")
…

and somewhere in ~/offlineimap.py add import keyring. Now all you have to do is set your password, like so:

$ python2 
>>> import keyring
>>> keyring.set_password("offlineimap","username@host.net", "MYPASSWORD")'

and it'll grab the password from your (kwallet/gnome-) keyring instead of having to keep it in plaintext or enter it each time.

Emacs EasyPG

See http://www.emacswiki.org/emacs/OfflineIMAP#toc2

Kerberos authentication

Install python2-kerberos from AUR and do not specify remotepass in your .offlineimaprc. OfflineImap figure out the reset all if have a valid Kerberos TGT. If you have 'maxconnections', it will fail for some connection. Comment 'maxconnections' out will solve this problem.

Troubleshooting

Overriding UI and autorefresh settings

For the sake of troubleshooting, it is sometimes convenient to launch offlineimap with a more verbose UI, no background syncs and perhaps even a debug level:

$ offlineimap [ -o ] [ -d <debug_type> ] [ -u <ui> ]

-o

Disable autorefresh, keepalive, etc.

-d <debug_type>

Where <debug_type> is one of imap, maildir or thread. Debugging imap and maildir are, by far, the most useful.

-u <ui>

Where <ui> is one of CURSES.BLINKENLIGHTS, TTY.TTYUI, NONINTERACTIVE.BASIC, NONINTERACTIVE.QUIET or MACHINE.MACHINEUI. TTY.TTYUI is sufficient for debugging purposes.

Curses interface (Curses.Blinkenlights) locks terminal

Because of a bug in Python's ncurses package (http://bugs.python.org/issue7567) the Curses interface of OfflineIMAP breaks the terminal on exit. While it appears to irreparably lock the terminal, in reality it only prevents commands from being displayed. The bug has been fixed in Python's SVN for all versions 2.6 up to 3.2 but the current package in the repositories (Python 2.6.5) is still buggy.

In order to solve the issue:

• either append reset to OfflineIMAP's launch command:

$ offlineimap; reset

• or change the ui field in ~/.offlineimaprc to select a fully functional one:

ui = TTY.TTYUI

• or as quick workaround you can just use the following command to skip the reset() function in Curses.py which causes the problem

# sed -i '125i\ \ \ \ \ \ \ \ return' /usr/lib/python2.6/site-packages/offlineimap/ui/Curses.py

netrc authentication

There are some bugs in the current offlineimap which makes it impossible to read the authentication data from ~/.netrc if there are multiple Accounts per remote machine. ( see Mail Archive ) But they are fixed in the GIT package offlineimap-git^AUR (note that is AUR package is flagged as out of date; see the current GitHub external link below). Using the package you can collect all passwords in ~/.netrc. And do not forget to set it's access rights:

chmod 600 ~/.netrc

An example netrc file would be

~/.netrc

machine mail.myhost.de
    login mr_smith
    password secret

socket.ssl deprecation warnings

Depending on the currently installed python version, running offlineimap throws this warning:

DeprecationWarning: socket.ssl() is deprecated.  Use ssl.wrap_socket() instead.

This can be particularly annoying when offlineimap's output is being logged or mailed through cron.

To fix the problem, apply this upstream patch or install offlineimap-git^AUR:

--- offlineimap/imaplibutil.py.orig	2009-08-12 01:24:23.000000000 -0430
+++ offlineimap/imaplibutil.py		2010-06-07 11:17:37.849038683 -0430
@@ -23,9 +23,11 @@
 # Import the symbols we need that aren't exported by default
 from imaplib import IMAP4_PORT, IMAP4_SSL_PORT, InternalDate, Mon2num
 
-# ssl is new in python 2.6
-if (sys.version_info[0] == 2 and sys.version_info[1] >= 6) or sys.version_info[0] >= 3:
+try:
     import ssl
+    ssl_wrap = ssl.wrap_socket
+except ImportError:
+    ssl_wrap = socket.ssl
 
 class IMAP4_Tunnel(IMAP4):
     """IMAP4 client class over a tunnel
@@ -169,7 +171,7 @@
         if last_error != 0:
             # FIXME
             raise socket.error(last_error)
-        self.sslobj = socket.ssl(self.sock, self.keyfile, self.certfile)
+        self.sslobj = ssl_wrap(self.sock, self.keyfile, self.certfile)
         self.sslobj = sslwrapper(self.sslobj)
 
 mustquote = re.compile(r"[^\w!#$%&'+,.:;<=>?^`|~-]")

The diff is relative to the root buildir and it can be applied by using ABS.

Folder could not be created

In version 6.5.3, offlineimap gained the ability to create folders in the remote repository, as described here.

This can lead to errors of the following form when using nametrans on the remote repository:

ERROR: Creating folder bar on repository foo-remote
  Folder 'bar'[foo-remote] could not be created. Server responded: ('NO', ['[ALREADYEXISTS] Duplicate folder name bar (Failure)'])

The solution is to provide an inverse nametrans lambda for the local repository, e.g.

~/.offlineimaprc

[Repository foo-local]
nametrans = lambda foldername: foldername.replace('bar', 'BAR')

[Repository foo-remote]
nametrans = lambda foldername: foldername.replace('BAR', 'bar')

• For working out the correct inverse mapping. the output of offlineimap --info should help.
• After updating the mapping, it may be necessary to remove all of the folders under $HOME/.offlineimap/ for the affected accounts.

SSL fingerprint does not match

 ERROR: Server SSL fingerprint 'keykeykey' for hostname 'example.com' does not match configured fingerprint. Please verify and set 'cert_fingerprint' accordingly if not set yet.

To solve this, add to ~/.offlineimaprc (in the same section as ssl = yes) one of the following:

• either add cert_fingerprint, with the certificate fingerprint of the remote server. This checks whether the remote server certificate matches the given fingerprint.

 cert_fingerprint = keykeykey

• or add sslcacertfile with the path to the system CA certificates file. Needs ca-certificates installed. This validates the remote ssl certificate chain against the Certification Authorities in that file.

 sslcacertfile = /etc/ssl/certs/ca-certificates.crt

External links

• Official OfflineIMAP mailing list
• Gnus, Dovecot, OfflineIMAP, search: a HOWTO
  • This setup worked for me, only difference being I had to add mail_location = maildir:~/Maildir to /etc/dovecot/dovecot.conf. Also, I used the Gmail configuration above. --Unhammer 09:24, 22 October 2010 (EDT)
• Mutt + Gmail + Offlineimap
  • An outline of brisbin's simple gmail/mutt setup using cron to keep offlineimap syncing.
• Current OfflineIMAP maintainer's fork on GitHub
  • Note that a strict build of this on current Arch will fail due to python references unless they are replaced with python2