OfflineIMAP Manual - Powerful IMAP/Maildir synchronization and reader support
Most configuration is done via the configuration file. Nevertheless, there are a few command-line options that you may set for
-1 Disable most multithreading operations
Use solely a single-connection sync. This effectively sets the maxsyncaccounts and all maxconnections configuration file variables
Sets OfflineIMAP into profile mode. The program will create profiledir (it must not already exist). As it runs, Python profiling
information about each thread is logged into profiledir. Please note: This option is present for debugging and optimization only,
and should NOT be used unless you have a specific reason to do so. It will significantly slow program performance, may reduce reli-
ability, and can generate huge amounts of data. You must use the -1 option when you use -P.
Overrides the accounts option in the general section of the configuration file. You might use this to exclude certain accounts, or
to sync some accounts that you normally prefer not to. Separate the accounts by commas, and use no embedded spaces.
Specifies a configuration file to use in lieu of the default, ~/.offlineimaprc.
Enables debugging for OfflineIMAP. This is useful if you are trying to track down a malfunction or figure out what is going on
under the hood. I suggest that you use this with -1 to make the results more sensible.
-d requires one or more debugtypes, separated by commas. These define what exactly will be debugged, and include three options:
imap, maildir, and thread. The imap option will enable IMAP protocol stream and parsing debugging. Note that the output may con-
tain passwords, so take care to remove that from the debugging output before sending it to anyone else. The maildir option will
enable debugging for certain Maildir operations. And thread will debug the threading model.
Only sync the specified folders. The foldernames are the untranslated foldernames. This command-line option overrides any folder-
filter and folderincludes options in the configuration file.
Override configuration file option. If "section" is omitted, it defaults to general. Any underscores "_" in the section name are
replaced with spaces: for instance, to override option autorefresh in the "[Account Personal]" section in the config file one would
use "-k Account_Personal:autorefresh=30". You may give more than one -k on the command line if you wish.
Enables logging to filename. This will log everything that goes to the screen to the specified file. Additionally, if any debug-
ging is specified with -d, then debug messages will not go to the screen, but instead to the logfile only.
-o Run only once,
ignoring all autorefresh settings in the configuration file.
-q Run only quick synchronizations.
Ignore any flag updates on IMAP servers.
-h|--help Show summary of options.
Specifies an alternative user interface module to use. This overrides the default specified in the configuration file. The
pre-defined options are listed in the User Interfaces section. The interface name is case insensitive.
OfflineIMAP has various user interfaces that let you choose how the program communicates information to you. The 'ui' option in the config-
uration file specifies the user interface. The -u command-line option overrides the configuration file setting. The available values for
the configuration file or command-line are described in this section.
Blinkenlights is an interface designed to be sleek, fun to watch, and informative of the overall picture of what OfflineIMAP is doing. I
consider it to be the best general-purpose interface in OfflineIMAP.
Blinkenlights contains a row of "LEDs" with command buttons and a log. The log shows more detail about what is happening and is
color-coded to match the color of the lights.
Each light in the Blinkenlights interface represents a thread of execution -- that is, a particular task that OfflineIMAP is performing
right now. The colors indicate what task the particular thread is performing, and are as follows:
Black: indicates that this light's thread has terminated; it will light up again later when new threads start up. So, black indicates no
Red (Meaning 1):
is the color of the main program's thread, which basically does nothing but monitor the others. It might remind you of HAL 9000
Gray: indicates that the thread is establishing a new connection to the IMAP server.
is the color of an account synchronization thread that is monitoring the progress of the folders in that account (not generating
Cyan: indicates that the thread is syncing a folder.
Green: means that a folder's message list is being loaded.
Blue: is the color of a message synchronization controller thread.
indicates that an actual message is being copied. (We use fuchsia for fake messages.)
Red (meaning 2):
indicates that a message is being deleted.
Yellow / bright orange:
indicates that message flags are being added.
Pink / bright red:
indicates that message flags are being removed.
Red / Black Flashing:
corresponds to the countdown timer that runs between synchronizations.
The name of this interfaces derives from a bit of computer history. Eric Raymond's Jargon File defines blinkenlights, in part, as:
Front-panel diagnostic lights on a computer, esp. a dinosaur. Now that dinosaurs are rare, this term usually refers to status lights on
a modem, network hub, or the like.
This term derives from the last word of the famous blackletter-Gothic sign in mangled pseudo-German that once graced about half the com-
puter rooms in the English-speaking world. One version ran in its entirety as follows:
ACHTUNG! ALLES LOOKENSPEEPERS!
Das computermachine ist nicht fuer gefingerpoken und mittengrabben.
Ist easy schnappen der springenwerk, blowenfusen und poppencorken
mit spitzensparken. Ist nicht fuer gewerken bei das dumpkopfen.
Das rubbernecken sichtseeren keepen das cotten-pickenen hans in das
pockets muss; relaxen und watchen das blinkenlichten.
TTYUI interface is for people running in basic, non-color terminals. It prints out basic status messages and is generally friendly to use
on a console or xterm.
Basic is designed for situations in which OfflineIMAP will be run non-attended and the status of its execution will be logged. You might
use it, for instance, to have the system run automatically and e-mail you the results of the synchronization. This user interface is not
capable of reading a password from the keyboard; account passwords must be specified using one of the configuration file options.
Quiet is designed for non-attended running in situations where normal status messages are not desired. It will output nothing except
errors and serious warnings. Like Basic, this user interface is not capable of reading a password from the keyboard; account passwords
must be specified using one of the configuration file options.
MachineUI generates output in a machine-parsable format. It is designed for other programs that will interface to OfflineIMAP.
OfflineImap listens to the unix signals SIGUSR1 and SIGUSR2.
If sent a SIGUSR1 it will abort any current (or next future) sleep of all accounts that are configured to "autorefresh". In effect, this
will trigger a full sync of all accounts to be performed as soon as possible.
If sent a SIGUSR2, it will stop "autorefresh mode" for all accounts. That is, accounts will abort any current sleep and will exit after a
currently running synchronization has finished. This signal can be used to gracefully exit out of a running offlineimap "daemon".
SSL3 write pending:
users enabling SSL may hit a bug about "SSL3 write pending". If so, the account(s) will stay unsynchronised from the time the bug
appeared. Running OfflineIMAP again can help. We are still working on this bug. Patches or detailed bug reports would be appreci-
ated. Please check you're running the last stable version and send us a report to the mailing list including the full log.
o IDLE support is incomplete and experimental. Bugs may be encountered.
o No hook exists for "run after an IDLE response". Email will show up, but may not be processed until the next refresh cycle.
o nametrans may not be supported correctly.
o IMAP IDLE <-> IMAP IDLE doesn't work yet.
o IDLE may only work "once" per refresh. If you encounter this bug, please send a report to the list!
Maildir support in Windows drive
Maildir uses colon caracter (:) in message file names. Colon is however forbidden character in windows drives. There are sev-
eral workarounds for that situation:
Use maildir-windows-compatible = yes account OfflineIMAP configuration.
o That makes OfflineIMAP to use exclamation mark (!) instead of colon for storing messages. Such files can be written to
windows partitions. But you will probably loose compatibility with other programs trying to read the same Maildir.
o Exclamation mark was choosed because of the note in http://docs.python.org/library/mailbox.html
o If you have some messages already stored without this option, you will have to re-sync them again
Enable file name character translation in windows registry (not tested)
Use cygwin managed mount (not tested)
o not available anymore since cygwin 1.7
By default, we use fairly conservative settings that are good for syncing but that might not be the best performing one. Once you got
everything set up and running, you might want to look into speeding up your synchronization. Here are a couple of hints and tips on how to
1. Use maxconnections > 1. By default we only use one connection to an IMAP server. Using 2 or even 3 speeds things up considerably in
most cases. This setting goes into the [Repository XXX] section.
2. Use folderfilters. The quickest sync is a sync that can ignore some folders. I sort my inbox into monthly folders, and ignore every
folder that is more than 2-3 months old, this lets me only inspect a fraction of my Mails on every sync. If you haven't done this
yet, do it :). See the folderfilter section the example offlineimap.conf.
3. The default status cache is a plain text file that will write out the complete file for each single new message (or even changed
flag) to a temporary file. If you have plenty of files in a folder, this is a few hundred kilo to megabytes for each mail and is
bound to make things slower. I recommend to use the sqlite backend for that. See the status_backend = sqlite setting in the example
offlineimap.conf. You will need to have python-sqlite installed in order to use this. This will save you plenty of disk activity. Do
note that the sqlite backend is still considered experimental as it has only been included recently (although a loss of your status
cache should not be a tragedy as that file can be rebuild automatically)
4. Use quick sync. A regular sync will request all flags and all UIDs of all mails in each folder which takes quite some time. A 'quick'
sync only compares the number of messages in a folder on the IMAP side (it will detect flag changes on the Maildir side of things
though). A quick sync on my smallish account will take 7 seconds rather than 40 seconds. Eg, I run a cron script that does a regular
sync once a day, and does quick syncs inbetween.
5. Turn off fsync. In the [general] section you can set fsync to True or False. If you want to play 110% safe and wait for all opera-
tions to hit the disk before continueing, you can set this to True. If you set it to False, you lose some of that safety trading it
SECURITY AND SSL
Some words on OfflineImap and its use of SSL/TLS. By default, we will connect using any method that openssl supports, that is SSLv2, SSLv3,
or TLSv1. Do note that SSLv2 is notoriously insecure and deprecated. Unfortunately, python2 does not offer easy ways to disable SSLv2. It
is recommended you test your setup and make sure that the mail server does not use an SSLv2 connection. Use e.g. "openssl s_client -host
mail.server -port 443" to find out the connection that is used by default.
Unfortunately, by default we will not verify the certificate of an IMAP TLS/SSL server we connect to, so connecting by SSL is no guarantee
against man-in-the-middle attacks. While verifying a server certificate fingerprint is being planned, it is not implemented yet. There is
currently only one safe way to ensure that you connect to the correct server in an encrypted manner: You can specify a 'sslcacertfile' set-
ting in your repository section of offlineimap.conf pointing to a file that contains (among others) a CA Certificate in PEM format which
validating your server certificate. In this case, we will check that: 1) The server SSL certificate is validated by the CA Certificate 2)
The server host name matches the SSL certificate 3) The server certificate is not past its expiration date. The FAQ contains an entry on
how to create your own certificate and CA certificate.
If you have not configured your account to connect via SSL anyway, OfflineImap will still attempt to set up an SSL connection via the
STARTTLS function, in case the imap server supports it. Do note, that there is no certificate or fingerprint checking involved at all, when
using STARTTLS (the underlying imaplib library does not support this yet). This means that you will be protected against passively listen-
ing eavesdroppers and they will not be able to see your password or email contents. However, this will not protect you from active attacks,
such as Man-In-The-Middle attacks which cause you to connect to the wrong server and pretend to be your mail server. DO NOT RELY ON START-
TLS AS A SAFE CONNECTION GUARANTEEING THE AUTHENTICITY OF YOUR IMAP SERVER!
John Goerzen <email@example.com>
2011-01-15 1 OFFLINEIMAP(MANUAL)