Re: offlineimap / uw-imapd / mutt

[John Goerzen <jgoerzen@xxxxxxxxxxxx>]

On Saturday, April 19, 2003 03:28 am, Sam Clegg wrote:
> I am a very happy user of offlineimap.  In fact I use it every 5 minutes
> to sync ~80 mail folders to my laptop.

Glad to hear it!

> However, when I ssh directly into the server to read my mail with mutt
> (when I don't have my laptop with me) the offlineimap.uidvalidity
> files for the folders that mutt writes messages to are corrupted the
> next time I try to sync.

Well, that's not quite what's happening.  Rather, what's happening is that the 
*server's* UID validity is getting messed up.

UW IMAPD is notorious for having this problem.  In a nutshell, here's why this 
matters:

IMAP servers assign a unique UID to each message in a folder.  That number is 
never reused.  That's how OfflineIMAP can match up a message on the server to 
a message on your local machine, so when you delete it, it knows without any 
doubt which message to delete on the server.

The server also has a "UID validity" number for each folder.  If that number 
ever changes, it's a signal to the client (OfflineIMAP) that any UIDs it's 
been using for that folder are now invalid.  This might happen, for instance, 
if you delete and recreate the folder -- the server may restart numbering 
from 1, so what used to be message 5 may no longer be.

OfflineIMAP detects a condition where the UID validity changes, and will skip 
syncing the folder in that case.  This is a data integrity measure.

> Is this normal?  Am I not supposed to manipulate directly (with mutt)
> my mail folders on the server?  Procmail seems to be able to write to

That depends on your server.  I run Courier and have no problems there.

When you log on to your server, you might try connecting to your mail store 
via mutt's IMAP support.  For instance, mutt -f '{localhost}' to get to your 
inbox.  Then you'd be accessing it the same way as OfflineIMAP, which 
*should* make things work better.

> these folders without upsetting offlineimap?  Perhaps this because
> I am using mbox and uw-imapd on the server.

I'd say the chances are about 90% that this is a problem with UW-IMAPD.

> Any help?  Should I switch to a different mta/imapd on the server?
> Anyone know of a good comparison on the various imapds in debian?

I have had very good luck with Courier.  It seems to have a complete IMAP 
implementation, no long track record of security holes, and a good deal of 
flexibility.  It's what I test OfflineIMAP against, too :-)

Courier does require Maildirs on the server.  However, procmail can deliver 
directly to Maildirs, and mutt can read them, so it shouldn't be a big 
problem.

If you do use Courier, bump up the MAXPERIP value in your config file.  
OfflineIMAP likes to open many connections to the server (if you tell it to 
with maxconnections), and Courier will limit this by default, which will 
interfere with OfflineIMAP.

-- John