Ubuntu Manpage: offlineimap - Synchronize mailboxes and Maildirs both ways or one either way.

Provided by: offlineimap_7.2.3+dfsg1-1ubuntu1_all

NAME

       offlineimap - Synchronize mailboxes and Maildirs both ways or one either way.

SYNOPSIS

       offlineimap (options)

DESCRIPTION

       Synchronize the accounts configured in the configuration file via IMAP. Each account has two sides. One
       of the side must be an IMAP server. The other side can either be a Maildir or another IMAP server.

       Works with Python 2.

OPTIONS

-h, --help
Display summary of options.

--version
Output version.

-V
Output offlineimap version and additional imaplib2 information.

--dry-run
Run in dry run mode.

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.

--info
Output information on the configured email repositories.

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 output the
debug information.

-1
Limit multithreading operations and run solely a single-thread sync.

This effectively sets the maxsyncaccounts and all maxconnections configuration file variables to 1
(the number).

-P <directory>
Set OfflineIMAP into profile mode.

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.

-a <account1[,account2[,...]]>
Overrides the accounts section in the config file.

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

-c <path/to/configuration_file>
Specifies a configuration file to use.

-d <type1[,type2[,...]]>
Enables debugging for OfflineIMAP.

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 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’.

-l <path/to/file.log>
Send logs to <file.log>.

-s
Send logs to syslog.

-f <folder1[,folder1[,...]]>
Only sync the specified folders.

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.

-k <[section:]option=value
Override any 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’. Repeat this option as much as
necessary to redefine multiple options.

-o
Run only once.

Ignore any autorefresh setting in the configuration file.

-q
Run only quick synchronizations.

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.

-u <UI>
Specifies an alternative user interface to use.

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.

--delete-folder
Delete a folder on the remote repository.

Only one account must be specified/configured for this feature to work or you must provide one
account with -a. The folder name must be provided with the remote separators (likely /) in UTF-8 if
utf8foldernames is enabled or in IMAP otherwise. E.g.: "Remote/folder/name".

--migrate-fmd5-using-nametrans
Migrate FMD5 hashes from versions prior to 6.3.5.

The way that FMD5 hashes are calculated was changed in version 6.3.5 (now using the nametrans folder
name) introducing a regression which may lead to re-uploading all messages. Try and fix the above
regression by calculating the correct FMD5 values and renaming the corresponding messages.

Caution
Since the FMD5 part of the filename changes, this may lead to UID conflicts. Ensure to dispose a
proper backup of both the cache and the Maildir before running this fix as well as verify the results
using the ‘--dry-run’ flag first.

--mbnames-prune
Remove dangling entries for removed accounts or if mbnames is not enabled/used anymore.

Internally, offlineimap build intermediate mbnames files. They are added automatically when mbnames
is enabled. However, disabling accounts so they are not synced anymore does not necessarily means
they should be removed from the file built by mbnames. It is required to start offlineimap with this
CLI option each time accounts are removed. When run, any account not in the accounts configuration
option are removed in the mbnames file.

It is possible to manually remove intermediate files in <metadata>/mbnames/.

Notice this option honors --dry-run.

CONFIGURATION

       For full details of the available configuration options, please refer to
       /usr/share/doc/offlineimap/examples/offlineimap.conf.gz.

SYNCHRONIZATION PERFORMANCE

By default, we use fairly conservative settings that are safe 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 achieve this.

1. Synchronize more than one account.

By default we only use one connection to an IMAP server. Using 2 or even 3 speeds things up
considerably in most cases. In order to synchronize more than one account concurrently, consider
starting one instance of offlineimap per account.

Warning
enabling the maxsyncaccounts and maxconnections options is deprecated since it’s known to have
race conditions.

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 in
offlineimap.conf.

3. The sqlite cache.

OfflineImap caches the state of the synchronisation to e.g. be able to determine if a mail has been
added or deleted on either side.

The historical status cache was a plain text file that was writing out the complete file for each
single new message (or even changed flag) to a temporary file. If there was plenty of files in a
folder this was bound to make things slow. The latest status cache is sqlite. This saves plenty of
disk activity.

The historical plain status cache is not supported anymore but migrating from a very old installation
using the plain text cache is still supported. In this case, you may want to delete the old cache
directory in <metadata>/Account-<account>/LocalStatus manually (the sqlite cache stands in the
LocalStatus-sqlite folder). First, make sure you have run the new version of offlineimap for all your
accounts so that the status cache was migrated.

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. E.g. run a cron script that does a regular sync once a day, and does
quick syncs ‘-q’ only synchronizing the ‘-f INBOX’ in between.

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 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.

SECURITY AND SSL

By default, OfflineIMAP 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.

• Certificate checking

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:

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 has an entry on how to create your own certificate and CA certificate.

• StartTLS

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!

UNIX SIGNALS

       OfflineImap listens to the unix signals SIGUSR1, SIGUSR2, SIGTERM, SIGINT, SIGHUP, SIGQUIT.

       •   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 or SIGABRT, 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".

       •   SIGTERM, SIGINT, SIGHUP are all treated to gracefully terminate as soon as possible. This means it
           will finish syncing the current folder in each account, close keep alive connections, remove locks on
           the accounts and exit.

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

           More than one SIGTERM will behave like SIGQUIT.

       •   If sent SIGQUIT, dumps stack traces for all threads and tries to dump process core.

KNOWN ISSUES

• Deletions.

While in usual run the deletions are propagated. To prevent from data loss, removing a folder makes
offlineimap re-sync the folder. However, propagating the removal of the whole content of a folder can
happen in the two following cases:

• The whole content of a folder is deleted but the folder directory still exists.

• The parent directory of the folder was deleted.

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

• IDLE support is incomplete and experimental. Bugs may be encountered.

• No hook exists for "run after an IDLE response".

Email will show up, but may not be processed until the next refresh cycle.

• nametrans may not be supported correctly.

• IMAP IDLE <→ IMAP IDLE doesn’t work yet.

• IDLE might stop syncing on a system suspend/resume.

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

1. Enable file name character translation in windows registry (not tested).

• http://support.microsoft.com/kb/289627

2. Use cygwin managed mount (not tested).

• not available anymore since cygwin 1.7

3. Use "maildir-windows-compatible = yes" account OfflineIMAP configuration.

• 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.

• Exclamation mark was chosen because of the note in
http://docs.python.org/library/mailbox.html

• If you have some messages already stored without this option, you will have to re-sync them
again

• OfflineIMAP confused after system suspend.

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.

• OfflineIMAP confused when mails change while in a sync.

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.

• Sharing a maildir with multiple IMAP servers.

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.

• Edge cases with maxage causing too many messages to be synced.

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.

• Offlineimap hangs.

When having unexpected hangs it’s advised to set ‘singlethreadperfolder’ to yes, especially when in
IMAP/IMAP mode (no maildir).

• Passwords in netrc.

Offlineimap doesn’t know how to retrieve passwords when more than one account is stored in the netrc
file. See https://github.com/OfflineIMAP/offlineimap/issues/295.

• XOAUTH2

XOAUTH2 might be a bit tricky to set up. Make sure you’ve followed the step to step guide in
offlineimap.conf. The known bugs about Gmail are tracked at
https://github.com/OfflineIMAP/offlineimap/labels/Gmail.

Sometimes, you might hit one of the following error:

• [imap]: xoauth2handler: response "{u’error': u’invalid_grant'}"

• oauth2handler got: {u’error': u’invalid_grant'}

In such case, we had reports that generating a new refresh token from the same client ID and secret
can help.

Google documentation on "invalid_grant".

When you try to use a refresh token, the following returns you an
invalid_grant error:

- Your server's clock is not in sync with network time protocol - NTP.
- The refresh token limit has been exceeded.

Token expiration.

It is possible that a granted token might no longer work. A token might stop
working for one of these reasons:

- The user has revoked access.
- The token has not been used for six months.
- The user changed passwords and the token contains Gmail scopes.
- The user account has exceeded a certain number of token requests.

There is currently a limit of 50 refresh tokens per user account per client. If
the limit is reached, creating a new token automatically invalidates the oldest
token without warning. This limit does not apply to service accounts.

See https://developers.google.com/analytics/devguides/config/mgmt/v3/authorization and
https://developers.google.com/identity/protocols/OAuth2#expiration to know more.

• "does not have message with UID" with Microsoft servers

`ERROR: IMAP server 'Server ### Remote' does not have a message with UID 'xxx'`

Microsoft IMAP servers are not compliant with the RFC. It is currently required to folderfilter some
faulting folders. See http://www.offlineimap.org/doc/FAQ.html#exchange-and-office365 for a detailed
list.

MAIN AUTHORS

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