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Improving Modest email sync reliability

Latest revision as of 14:19, 24 October 2010

Lots of complains have been reported regarding Modest N900 email client. Particularly when it comes to sync emails. Quoting DaveQB:

1. It takes about 20mins to check my email.
2. It uses 100% cpu for the entire time it is checking.
3. Email that is read, deleted etc are not updated on the server-side, so when I check on a different client later, nothing I did on the N900 is reflected.
4. You can't do any searching.
5. It doesn't respect subscribed folder settings on the server

I basically faced all these problems, but synchronization is the top most important one for me. This page is about trying to improve Modest email sync reliability and exploring other ways to read/write emails on N900. It mainly focuses on dealing with IMAP from a GMail account, but may be extended to other IMAP, and even other protocols such as POP.

[edit] Disclaimer

Following instructions are provided as-is. Use them as you like and at your own risk. I'm not responsible of any emails losses or anything like that. You've been warned.

[edit] Prerequisites

Before diving into details, you should be comfortable writing commands on terminal, editing files, etc... some basic Linux usage is required.

Because we'll write a lot, you may want to access your N900 through SSH. In order to do this, you'll need to deal with USB_networking between your PC and your phone.

Finally, you should know how to access your IMAP account, that is, all parameters should been known to work to avoid any doubts when testing your connection.

[edit] Accessing a IMAP GMail account using mutt

So my first try was accessing my GMail account using mutt. There have been discussions about this here, though I couldn't find a deb package file for mutt in different repository. I had to create a new one, including some needed compilation option:

• slang: allowing 256 terminal colors, reported to work better than curses
• hcache: header caching enable, preventing always accessing remote IMAP account to list emails
• imap: because we want to access an IMAP account...
• ssl: because this IMAP account is an IMAPS account (using SSL encryption)

This deb file can be found, see links section at the end of this page.

First, copy mutt deb file to your N900 (scp, mail, etc...) and install it as root:

sudo gainroot
dpkg -i mutt_1.5.20-2_armel.deb

You then need to write your .muttrc file to setup your IMAP account connection. Here's my basic muttrc file I used to access my Gmail account:

# General
set move=no
set quit=ask-yes
set timeout=15
auto_view text/html
set realname="Sebastien Lelong"

# IMAP
set imap_authenticators="login"
set imap_passive="no"
set imap_user = 'username'
set imap_pass = 'password'
set spoolfile = imaps://imap.gmail.com:993/INBOX
set folder = imaps://imap.gmail.com:993
set record="imaps://imap.gmail.com/[Gmail]/Sent Mail"
set maildir_trash = yes
set postponed="imaps://imap.gmail.com/[Gmail]/Drafts"
set header_cache = yes
set smtp_url = smtp://username@gmail.com@smtp.gmail.com:587/
set smtp_pass = "password"

Replace username and password as needed. Launch mutt:

mutt

you'll be asked to confirm something about a certificate, then mutt will access your IMAP account and retrieve headers for all your emails. Yes, all headers (but not emails content...) ! There may be an option to only retrieve last email headers (only emails X days old), but I just don't know it. This can take quite a lot of time and kills your dataplan... Luckily this occurs only once: mutt is creating its header cache. When running again, mutt will just re-analyze its cache, locally. This can take quite some time anyway, when you have a large mailbox.

Using mutt like this is unfortunately not that nice:

• your network connection must be fast, because browsing emails will constantly make network connection to the remote IMAP account
• worst case, when you don't have network connection, you just can't read your emails, even old ones...

[edit] offlineimap to read emails when no network connection is available

While one major advantage to IMAP protocol is being able to directly and remotely access emails on an account, when you don't have any network connection, you just can't access them... A workaround is to use a tool like OfflineIMAP, which can synchronize an IMAP account with a local maildir.

This sync occurs both ways: changes on IMAP account will propagate to maildir, changes on maildir will propagate to IMAP account. This ensure what you'll locally read will also be marked as read on the IMAP server.

In order to use offlineimap, I had to get last sources including patches to select only emails not olders than X days. This will prevent getting *all* emails from the server (headers and bodies)... offlineimap package is available from extra-devel repository (optified to save some rootfs space). Install it as root:

sudo gainroot
apt-get install offlineimap
exit

Once installed, you'll need to create ~/.offlineimaprc in order to define remote IMAP and local maildir accounts. Here's mine, again minimalist. See offlineimap.conf on OfflineIMAP website to figure out possible options.

[general]
accounts = GMail
ui = Noninteractive.Basic 
socktimeout = 300

[Account GMail]
localrepository = Local
remoterepository = Remote
maxage = 5
 
[Repository Local]
type = Maildir
localfolders = ~/Mail/GMail 
sep = /
 
[Repository Remote]
type = Gmail
remoteuser = username
remotepass = password
realdelete = no
trashfolder = [Gmail].Trash
folderfilter = lambda foldername: foldername in ['INBOX', '[Gmail]/Brouillons','[Gmail]/Suivis']
nametrans = lambda foldername: foldername.replace("[Gmail]/","")

We are basically telling offlineimap to sync a GMail IMAP account on a local maildir located in ~/Mail/GMail. Only emails younger than 5 days will be considered. Only directories listed folderfilter will be synced. This is useful when you lots of GMail labels but don't want to sync every of them (this can take quite some time and bandwidth, depending your dataplan). Also, instead of having "[Gmail]/Suivis" directories, I prefer (and Modest too, see later) only having a "Suivis" directory. nametrans is used to translate local dirs, here we're telling it to remove the "[Gmail]/" part.

Also create maildir location:

mkdir ~/Mail/GMail

Finally, because my deb packaging isn't that good, let's create a wrapper bash script to run offlineimap:

#!/bin/bash
offlineimap 2>&1 | tee /tmp/offlineimap.log
echo Last run: `/bin/date`

Save this script in ~/bin (for instance) as "syncemail.sh", and make executable:

chmod +x syncemail.sh

Each time it's launched, you can check what it does looking as /tmp/offlineimap.log.

Time to test. Run it !

./bin/syncemail.sh

Once it's done, you can run mutt to check what it retrieved, telling to access a maildir:

mutt -f ~/Mail/GMail/INBOX

If it sounds good to you, you can program a task, for instance using Alarmed, and configure it to run this script every X minutes. If you don't plan or don't care having a GUI to setup this interval, you can also let offlineimap regularly check emails. In the account section, you can add something like:

[account GMail]
...
autorefresh = 15

this will tell offlineimap to sync every 15 minutes. Since it'll always run, you need to "daemonize" it when starting it. This upstart script can be saved as /etc/event.d/offlineimap to start it at boot time:

start on started hildon-desktop
stop on starting shutdown
service
console none
exec su user -c /home/user/bin/syncemail.sh
post-stop script
    kill `cat /home/user/.offlineimap/pid`
end script

CAREFUL: in syncemail.sh script, offlinemap will log into /tmp/offlineimap.log. Since we're daemonizing it, it'll run indefinitely. This log file may become huge. When fully tested, you should remove "2>&1 | tee /tmp/offlineimap.log" from syncemail.sh script. Also, post-stop step is here to actually kill the offlineimap python script, else only the bash launcher, syncemail.sh, will be killed, not the python process it runs.

So far so good, we have our emails synced. We can read them using mutt. Still, we may like to use a graphical front-end, fully integrated to N900 system (applet, widgets, contacts, etc...).

[edit] Adding dovecot IMAP server to let Modest accessing emails locally

If only Modest could directly access our local maildir... Since it only support POP and IMAP account, we could install a local IMAP server, serving our maildir. Modest would then access this local IMAP server. This way, the remote sync part is delegated to offlineimap, while we can still use GUI front-ends. You'll still need to tell Modest to sync to the local maildir to check new emails. A short interval, 5 min, will ensure it'll be able to sync (since it's local, there's no network related issue anymore).

So, there are many IMAP server out there, I found dovecot to be easy to package and use. dovecot can be found in extra-devel (also optified to save rootfs space). Install it as root

sudo gainroot
apt-get install dovecot
exit

Copy example configuration:

sudo gainroot
cp /usr/local/etc/dovecot-example.conf /usr/local/etc/dovecot.conf

Dovecot is very powerful, you can set a lot of parameters. I tried to keep it as simple as possible. Dovecot will /etc/passwd as it's user/password database. Here's my dovecot.conf file:

base_dir = /var/run/dovecot/
protocols = imap
listen = 127.0.0.1
disable_plaintext_auth = no
ssl = no
login_user = dovecot
mail_location = maildir:~/Mail/GMail/INBOX

protocol imap {
}

auth default {
 
   mechanisms = plain
 
   passdb passwd {
   }
 
   userdb passwd {
   }

   user = root
}

Note dovecot will serve INBOX only (more work/search to be done in order to serve multiple maildirs...). Since we'll use it locally, we can specify an IP address to listen. Else you (or someone else) could access your IMAP account using Wifi for instance.

You can check configuration file syntax by running:

dovecot -n

Dovecot auth will be done under user "dovecot". We need to create it:

sudo gainroot
useradd -g mail dovecot

Also, we will access maildir from Modest email client. This maildir is owned by user "user". This user doesn't have any password, but Modest won't allow you not specifying one. We thus need to set it (I'm not sure about potential side effects of setting a password for this default user. So far I haven't had any problems, but...):

sudo gainroot
passwd user

Launch dovecot, as root

sudo gainroot
/usr/local/sbin/dovecot

Test it's running with telnet:

telnet 127.0.0.1 143

should give something like:

* OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE AUTH=PLAIN] Dovecot ready.

In order dovecot to be started at boot time, you can create this upstart script as /etc/event.d/dovecot

start on started hildon-desktop
stop on starting shutdown
service
console none
exec dovecot -F

Now open Modest, and add a new account:

Account name and name: whatever
username: user
password: yourpass
IMAP server: 127.0.0.1 # "localhost" won't be recognized as legal hostname...
IMAP: 143
No secure connection

About SMTP, you can use the one you're used to use. Another improvement would be to install a small local SMTP server, and let it send its emails when it can. So far SMTP sending works with Modest, so I didn't dig further.

[edit] Extra: defining subcriptions for Modest

When running, dovecot will create a "subscriptions" file into the maildir (I think it's dovecot). You can edit this file to add more directories to display within Modest GUI. For instance, my /home/user/Mail/GMail/subscriptions is:

INBOX
Brouillons
Suivis

Note: if you don't translate GMail folder, that is, if you keep "[Gmail].Suivis" for instance, Modest won't display directory correctly and split it as "[Gmail]" and ".Suivis". That's why I added a nametrans paramater on my offlineimaprc configuration file.

[edit] Conclusions

Using offlineimap and Dovecot, the synchronization process is removed from Modest email client. I'm still testing this configuration, it seems to work flawlessly. There are still issues and limitations:

• you can tell offlineimap to partially download emails, but you can't order it to fully download one specific emails (like on iPhone for instance). Attachments are also downloaded.
• some deb packaging would need to be improved. I did this quick & dirty
• you can't access different IMAP folders and different accounts. This would need to be improved, probably on dovecot side.
• "user" needs to have a password set. There can be unknown side effects. This could be avoid by setting a PAM authentication in dovecot (doesn't use /etc/passwd, no need to have a system user).
• it only deals with IMAP. Accessing POP account could be done the same way: instead of offlineimap, you could setup fetchmail or getmail and put retrieved emails in maildirs, just like here.
• ...

[edit] Where to find packages ?

dovecot, muut, msmtp and offlineimap used to be available from the following links:

• dovecot_1.2.11-1_armel.deb
• msmtp_1.4.20-1_armel.deb
• mutt_1.5.20-2_armel.deb
• offlineimap_6.2.1_all.deb

I've also created and uploaded deb packages for dovecot and offlineimap to extra-devel repository for convenience. You should prefer install them from extra-devel, as these packages are cleaner and optified (they install in /opt, not in / rootfs).

Hope it helps.

Cheers,

Seb

[edit] modest & offlineimap "shortcut"

I am currently experimenting with this setup:

• offlineimap synchronizes normally (as above)
• the local repository looks like this

type = Maildir
localfolders = ~/.modest/local_folders/

• just to be safe, the remote repository does a nametrans: 'x' + foldername
• the end result is, that I can see synchronized folders in modest

Does anybody see a problem with this? It seems to work as it should.

• it seems that modest sees new mails as new only when you enter the folder, not in the folder overview (which would mean that in the long run, having built-in offline storage is better)

Gruss, Christian

I don't know if it's the best place to comment but I tried to symlink ~/Mail/... with ~/.modest/local_folders/ and there were troubles (modest trying to create directory again ? I can't remember for sure). But this is interesting and could remove unnecessary complexity with dovecot. I'll try this setup !

Thanks & Cheers Seb