| Web site: | https://github.com/nicolas33/offlineimap |
|---|---|
| Copyright: | This document is licensed under GPLv2. |
Contents
This is a work in progress.
Please feel free to ask questions and/or provide answers; send email to the mailing list.
See the information on the Home page OfflineIMAP.
OfflineIMAP has a multithreaded sync, so it should have very nice performance.
OfflineIMAP versions 2.0 and above contain a multithreaded system. A good way to experiment is by setting maxsyncaccounts to 3 and maxconnections to 3 in each account clause.
This lets OfflineIMAP open up multiple connections simultaneously. That will let it process multiple folders and messages at once. In most cases, this will increase performance of the sync.
Don’t set the number too high. If you do that, things might actually slow down as your link gets saturated. Also, too many connections can cause mail servers to have excessive load. Administrators might take unkindly to this, and the server might bog down. There are many variables in the optimal setting; experimentation may help.
See the Performance section in the MANUAL for some tips.
It should run on most platforms supported by Python, with one exception: we do not support Windows, but some have made it work there.
The following has been reported by OfflineIMAP users. We do not test OfflineIMAP on Windows, so we can’t directly address their accuracy.
The basic answer is that it’s possible and doesn’t require hacking OfflineIMAP source code. However, it’s not necessarily trivial. The information below is based in instructions submitted by Chris Walker:
First, you must run OfflineIMAP in the Cygwin environment. The Windows filesystem is not powerful enough to accomodate Maildir by itself. Next, you’ll need to mount your Maildir directory in a special way. There is information for doing that at http://barnson.org/node/295. That site gives this example:: mount -f -s -b -o managed "d:/tmp/mail" "/home/of/mail" That URL also has more details on making OfflineIMAP work with Windows.
Not directly. Maildir was the easiest to implement. We are not planning to write an mbox-backend, though if someone sent me well-written mbox support and pledged to support it, it would be committed it to the tree.
However, OfflineIMAP can directly sync accounts on two different IMAP servers together. So you could install an IMAP server on your local machine that supports mbox, sync to it, and then instruct your mail readers to use the mboxes.
Or you could install whatever IMAP server you like on the local machine, and point your mail readers to that IMAP server on localhost.
IMAP servers use a folders UIDVALIDITY value in combination with a unique ID (UID) to refer to a specific message. This is guaranteed to be unique to a particular message forever. No other message in the same folder will ever get the same UID as long as UIDVALIDITY remains unchanged. UIDs are an integral part of OfflineIMAP's synchronization scheme; they are used to match up messages on your computer to messages on the server.
Sometimes, the UIDs on the server might get reset. Usually this will happen if you delete and then recreate a folder. When you create a folder, the server will often start the UID back from 1. But OfflineIMAP might still have the UIDs from the previous folder by the same name stored. OfflineIMAP will detect this condition because of the changed UIDVALIDITY value and skip the folder. This is GOOD, because it prevents data loss.
In the IMAP<->Maildir case, you can fix it by removing your local folder and cache data. For instance, if your folders are under ~/Folders and the folder with the problem is INBOX, you'd type this:
rm -r ~/Folders/INBOX rm -r ~/.offlineimap/Account-AccountName/LocalStatus/INBOX rm -r ~/.offlineimap/Repository-RemoteRepositoryName/FolderValidity/INBOX
(Of course, replace AccountName and RemoteRepositoryName with the names as specified in ~/.offlineimaprc).
Next time you run OfflineIMAP, it will re-download the folder with the new UIDs. Note that the procedure specified above will lose any local changes made to the folder.
Some IMAP servers are broken and do not support UIDs properly. If you continue to get this error for all your folders even after performing the above procedure, it is likely that your IMAP server falls into this category. OfflineIMAP is incompatible with such servers. Using OfflineIMAP with them will not destroy any mail, but at the same time, it will not actually synchronize it either. (OfflineIMAP will detect this condition and abort prior to synchronization.)
This question comes up frequently on the mailing list. You can find a detailed discussion of the problem there http://lists.complete.org/offlineimap@complete.org/2003/04/msg00012.html.gz.
OfflineIMAP does not currently provide this feature. You will have to delete folders manually. See next entry too.
OfflineIMAP does a two-way synchronization. That is, if you make a change to the mail on the server, it will be propagated to your local copy, and vise-versa. Some people might think that it would be wise to just delete all their local mail folders periodically. If you do this with OfflineIMAP, remember to also remove your local status cache (~/.offlineimap by default). Otherwise, OfflineIMAP will take this as an intentional deletion of many messages and will interpret your action as requesting them to be deleted from the server as well. (If you don't understand this, don't worry; you probably won't encounter this situation.)
OfflineIMAP is not designed to have several instances (for instance, a cron job and an interactive invocation) run over the same mailbox simultaneously. It will perform a check on startup and abort if another OfflineIMAP is already running. If you need to schedule synchronizations, you'll probably find autorefresh settings more convenient than cron. Alternatively, you can set a separate metadata directory for each instance. In the future, we will lock each account individually rather than having one global lock.
Normally, when you copy a message between folders or add a new message to a folder locally, OfflineIMAP will just do the right thing. However, sometimes this can be tricky ― if your IMAP server does not provide the SEARCH command, or does not return something useful, OfflineIMAP cannot determine the new UID of the message. So, in these rare instances, OfflineIMAP will upload the message to the IMAP server and delete it from your local folder. Then, on your next sync, the message will be re-downloaded with the proper UID. OfflineIMAP makes sure that the message was properly uploaded before deleting it, so there should be no risk of data loss.
But if you try to sync between two IMAP servers, where both are unable to provide you with UID of the new message, then this will lead to infinite loop. OfflineIMAP will upload the message to one server and delete on second. On next run it will upload the message to second server and delete on first, etc.
as follows:
4: [active] *Control: . 3: [ 4:36] personal: 2: [ 3:37] work: . 1: [ 6:28] uni: Simply press the appropriate digit (`3` for `personal`, etc.) to resync that account immediately. This will be ignored if a resync is already in progress for that account. 2) while in sleep mode, you can also send a SIGUSR1. See the `Signals on UNIX`_ section in the MANUAL for details.
Q: When synchronizing, I receive errors such as:
Folder 'sent'[main-remote] could not be created. Server responded:
('NO', ['Mailbox already exists.'])
to treat "special" folders as case insensitive (e.g. the initial INBOX. part, or folders such as "Sent" or "Trash"). If you happen to have a folder "sent" on one side of things and a folder called "Sent" on the other side, offlineimap will try to create those folders on both sides. If you server happens to treat those folders as case-insensitive you can then see this warning.
You can solve this by excluding the "sent" folder by filtering it from the repository settings:
folderfilter= lambda f: f not in ['sent']
Of course!
Just name them all in the accounts line in the general section of the configuration file, and add a per-account section for each one.
You can also optionally use the -a option when you run OfflineIMAP to request that it only operate upon a subset of the accounts for a particular run.
You do not need to. OfflineIMAP is smart enough to automatically figure out what folders are present on the IMAP server and synchronize them. You can use the folderfilter and nametrans configuration file options to request only certain folders and rename them as they come in if you like.
Also you can configure OfflineImap to only synchronize "subscribed" folders.
Use the folderfilter option. See the MANUAL for details and examples.
Some mail readers, such as mutt, are not capable of automatically determining the names of your mailboxes. OfflineIMAP can help these programs by writing the names of the folders in a format you specify. See the example offlineimap.conf for details.
You can verify an imapserver's certificate by specifying the CA certificate on a per-repository basis by setting the sslcacertfile option in the config file. (See the example offlineimap.conf for details.) If you do not specify any CA certificate, you will be presented with the server's certificate fingerprint and add that to the configuration file, to make sure it remains unchanged. No verification happens if connecting via STARTTLS.
The sslcacertfile file must contain an SSL certificate (or a concatenated certificates chain) in PEM format. (See the documentation of ssl.wrap_socket's certfile parameter for the gory details.) You can use either openssl or gnutls to create a certificate file in the required format.
^D
gnutls-cli --print-cert -p imaps ${host} </dev/null | sed -n | '/^-----BEGIN CERT/,/^-----END CERT/p' > $sslcacertfile
The path /etc/ssl/certs is not standardized; your system may store SSL certificates elsewhere. (On some systems it may be in /usr/local/share/certs/.)
Before using the resulting file, ensure that openssl verified the certificate successfully. In case of problems, you can test the certificate using a command such as (credits to Daniel Shahaf for this) to verify the certificate:
% openssl s_client -CAfile $sslcacertfile -connect ${hostname}:imaps 2>&1 </dev/null
If the server uses STARTTLS, pass the -starttls option and the 'imap' port.
In general, OfflineIMAP works with any IMAP server that provides compatibility with the IMAP RFCs. Some servers provide imperfect compatibility that may be good enough for general clients. OfflineIMAP needs more features, specifically support for UIDs, in order to do its job accurately and completely.
Any client that supports Maildir. Popular ones include mutt, Evolution and KMail. Thunderbird does not have maildir suppport.
With OfflineIMAP’s IMAP-to-IMAP syncing, this can be even wider; see the next question.
OfflineIMAP can work with Evolution. To do so, first configure your OfflineIMAP account to have sep = / in its configuration. Then, configure Evolution with the “Maildir-format mail directories” server type. For the path, you will need to specify the name of the top-level folder inside your OfflineIMAP storage location. You’re now set!
At this time, I believe that OfflineIMAP with Maildirs is not compatible with KMail. KMail cannot work in any mode other than to move all messages out of all folders immediately, which (besides being annoying and fundamentally broken) is incompatible with OfflineIMAP.
However, I have made KMail version 3 work well with OfflineIMAP by installing an IMAP server on my local machine, having OfflineIMAP sync to that, and pointing KMail at the same server.
Another way to see mails downloaded with offlineimap in KMail (KDE4) is to create a local folder (e.g. Backup) and then use ln -s localfolders_in_offlineimaprc ~/.kde/share/apps/kmail/mail/.Backup.directory. Maybe you have to rebuild the index of the new folder. Works well with KMail 1.11.4 (KDE4.x), offlineimap 6.1.2 and ArchLinux and sep = / in .offlineimaprc.
Other IMAP sync programs require you to do this. OfflineIMAP does not. You’ll get the best results without it, in fact, though turning it on won’t hurt anything.
The example offlineimap.conf file has this example. In your offlineimap.conf, you’ll list this:
[mbnames] enabled = yes filename = ~/Mutt/muttrc.mailboxes header = "mailboxes " peritem = "+%(accountname)s/%(foldername)s" sep = " " footer = "\n"
Then in your .muttrc:
source ~/Mutt/muttrc.mailboxes
You might also want to set:
set mbox_type=Maildir set folder=$HOME/Maildirpath
The OfflineIMAP manual has a more detailed example for doing this for multiple accounts.
To be brief:
For more information about the branching model and workflow, see the HACKING page.
OfflineIMAP has two relevant principles: 1) never modifying your messages in any way and 2) ensuring 100% reliable synchronizations. In order to do a reliable sync, OfflineIMAP must have a way to uniquely identify each e-mail. Three pieces of information are required to do this: your account name, the folder name, and the message UID. The account name can be calculated from the path in which your messages are. The folder name can usually be as well, BUT some mail clients move messages between folders by simply moving the file, leaving the name intact.
So, OfflineIMAP must store both a message UID and a folder ID. The folder ID is necessary so OfflineIMAP can detect a message being moved to a different folder. OfflineIMAP stores the UID (U= number) and an md5sum of the foldername (FMD5= number) to facilitate this.
This shell script will restart OfflineIMAP if it has crashed. Sorry, its written in Korn, so you’ll need ksh, pdksh, or mksh to run it:
#!/bin/ksh
# remove any old instances of this shell script or offlineimap
for pid in $(pgrep offlineimap)
do
if $pid -ne $$
then
kill $pid
fi
done
# wait for compiz (or whatever) to start and setup wifi
sleep 20
# If offlineimap exits, restart it
while true
do
( exec /usr/bin/offlineimap -u Noninteractive.Quiet )
sleep 60 # prevents extended failure condition
We don't have a testing tool, for now. As a IMAP client, we need an available IMAP server for that purpose. But it doesn't mean you can do anything.
Recent patches are merged in the next branch before beeing in the mainline. Once you have your own copy of the official repository, track this next branch:
git checkout -t origin/next
Update this branch in a regular basis with:
git checkout next git pull
Notice you're not supposed to install OfflineIMAP each time. You may simply run it like this:
./offlineimap.py
The choice is up to you. :-)
If you want to send regular patches, you should first subscribe to the mailing list. This is not a pre-requisite, though.
Next, you'll find documentation in the docs/ directory, especially the HACKING page.
You'll need to get a clone from the official OfflineIMAP repository and configure Git. Then, read the SubmittingPatches.rst page in your local repository or at https://github.com/nicolas33/offlineimap/blob/master/SubmittingPatches.rst#readme .
To send a patch, we recommend using 'git send-email'.
Depends. If you're not sure, it should start off of the master branch. master is the branch where new patches should be based on by default.
Obvious materials for next release (e.g. new features) start off of current next. Also, next is the natural branch to write patches on top of commits not already in master.
A fix for a very old bug or security issue may start off of maint. This isn't needed since such fix are backported by the maintainer, though.
Finally, a work on very active or current development can start from a topic next. This clearly means you need this topic as a base for what is intended.