dovecot - Oct 2006 - How Dovecot handles email changed by file operations

Hi,

We have been using Courier-imap for a few years. I am always in the
process of reviewing competing software, and hence my interest in
Dovecot.

Question: If email files are moved between IMAP folders (on the same
IMAP server or a different one) or deleted using shell scripts, how does
this impact Dovecot's indexes or its method of keeping track of the
email? How likely is index or file corruption or race condition? An
example, is the centralized removal of mail in all users' Junk folder
older than 30 days.

We use Maildir format and Dovecot 1.0-RC7 with Mysql. We have about 150
users. 

Thanks.
Craig

Craig Jackson wrote:
> Hi,
Hi Craig,
> Question: If email files are moved between IMAP folders (on the same
> IMAP server or a different one) or deleted using shell scripts, how
> does this impact Dovecot's indexes or its method of keeping track of
> the email? How likely is index or file corruption or race condition?
> An example, is the centralized removal of mail in all users' Junk
> folder older than 30 days.
As far as I know, if you add or remove files to a Maildir, then dovecot
will have no problem. It will rebuild the indexes as necessary. Besides
my IMAP client, I occasionally use mutt to access my Maildirs directly,
and haven't had a problem so far.

What _would_ cause a problem is if you modify the contents of a file in
a Maildir. Dovecot won't notice that, and the change (in the headers)
may not be propagated.

-- 
Anand

On 10.10.2006, at 20.20, Craig Jackson wrote:
> Question: If email files are moved between IMAP folders (on the same
> IMAP server or a different one) or deleted using shell scripts, how  
> does
> this impact Dovecot's indexes or its method of keeping track of the
> email? How likely is index or file corruption or race condition? An
> example, is the centralized removal of mail in all users' Junk folder
> older than 30 days.
Works just fine. Well, there is a very small possibility of readdir()  
syscall skipping some files if they're being moved exactly at the  
same time, which causes the mails to get temporarily lost, then in  
the next sync a couple of error messages will be written to Dovecot's  
logs and then they show up again. Courier has the exact same problem,  
but it just handles it silently (and worse than Dovecot by reusing  
UIDs that were already told to be expunged to clients).
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