offlineimap

Do not actually modify any store but check and print what synchronization actions would be taken if a sync would be performed. It will not precisely give the exact information what will happen. If e.g. we need to create a folder, it merely outputs Would create folder X, but not how many and which mails it would transfer.

Useful for debugging and bug reporting. Use in conjunction with the -a option to limit the output to a single account. This mode will prevent any actual sync to occur and exits after it outp ut the debug information.

This effectively sets the maxsyncaccounts and all maxconnections configuration file variables to 1. This is 1, the number.

The program will create DIR (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 decrease program performance, may reduce reliability, and can generate huge amounts of data. This option implies the -1 option.

Allows one to specify a particular account or set of accounts to sync without having to edit the config file.

This is useful if you are to track down a malfunction or figure out what is going on under the hood. This option requires one or more debugtypes, separated by commas. These define what exactly will be debugged, and so far include two options: imap, thread, maildir or ALL. The imap option will enable IMAP protocol stream and parsing debugging. Note that the output may contain 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. The use of any debug option (unless thread is included), implies the single-thread option -1.

The folder names are the untranslated foldernames of the remote repository. This command-line option overrides any folderfilter and folderincludes options in the configuration file.

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". Repeat this option as much as necessary to redefine multiple options.

Ignore any autorefresh setting in the configuration file.

Ignore any flag updates on IMAP servers. If a flag on the remote IMAP changes, and we have the message locally, it will be left untouched in a quick run. This option is ignored if maxage is set.

This overrides the default specified in the configuration file. The UI specified with -u will be forced to be used, even if checks determine that it is not usable. Possible interface choices are: quiet, basic, syslog, ttyui, blinkenlights, machineui.

This option is only applicable in non-verbose mode.

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.

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.

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 rebuilt automatically)

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 (-q) only synchronizing the "-f INBOX" in between.

In the [general] section you can set fsync to True or False. If you want to play 110% safe and wait for all operations to hit the disk before continuing, you can set this to True. If you set it to False, you lose some of that safety, trading it for speed.

This will convert your plain text cache to an sqlite cache (but leave the old plain text cache around for easy reverting). This must be quick and not involve any mail up/downloading.

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 checking the fingerprint is recommended. 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 setting 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:

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.

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 listening 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 STARTTLS AS A SAFE CONNECTION GUARANTEEING THE AUTHENTICITY OF YOUR IMAP SERVER!

It may take up to 10 seconds, if autorefresh option is used.

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 appreciated. Please check you’re running the last stable version and send us a report to the mailing list including the full log.

Maildir uses colon caracter (:) in message file names. Colon is however forbidden character in windows drives. There are several workarounds for that situation:

When resuming a suspended session, OfflineIMAP does not cleanly handles the broken socket(s) if socktimeout option is not set. You should enable this option with a value like 10.

When OfflineIMAP is syncing, some events happening since the invocation on remote or local side are badly handled. OfflineIMAP won’t track for changes during the sync.

Generally a word of caution mixing IMAP repositories on the same Maildir root. You have to be careful that you never use the same maildir folder for 2 IMAP servers. In the best case, the folder MD5 will be different, and you will get a loop where it will upload your mails to both servers in turn (infinitely!) as it thinks you have placed new mails in the local Maildir. In the worst case, the MD5 is the same (likely) and mail UIDs overlap (likely too!) and it will fail to sync some mails as it thinks they are already existent.

I would create a new local Maildir Repository for the Personal Gmail and use a different root to be on the safe side here. You could e.g. use

`~/mail/Pro` as Maildir root for the ProGmail and
`~/mail/Personal` as root for the personal one.

If you then point your local mutt, or whatever MUA you use to ~/mail/ as root, it should still recognize all folders.

All messages from at most maxage days ago (+/- a few hours, depending on timezones) are synced, but there are cases in which older messages can also be synced. This happens when a message’s UID is significantly higher than those of other messages with similar dates, e.g. when messages are added to the local folder behind offlineimap’s back, causing them to get assigned a new UID, or when offlineimap first syncs a pre-existing Maildir. In the latter case, it could appear as if a noticeable and random subset of old messages are synced.

John Goerzen, Sebastian Spaetz, Eygene Ryabinkin, Nicolas Sebrecht.

offlineimapui(7), openssl(1), signal(7), sqlite3(1).
http://offlineimap.org