[Dovecot] Modifying the underlying maildir externally (webmail, replication)

[Attila Nagy]

Tony Rutherford wrote:
> Timo Sirainen wrote:
>> On 20.1.2010, at 22.21, Attila Nagy wrote:
>>
>>  
>>> After running through http://wiki.dovecot.org/IndexFiles I'm not 
>>> sure how well would Dovecot work with other programs modifying the 
>>> maildirs (adding, deleting, moving messages, folders etc).
>>> The "Main index" section says "The index file is synchronized 
>>> against mailbox only if the syncing information changes.", where 
>>> syncing information consists or cur and new directories' timestamps.
>>> Does that mean I am safe there?
>>>     
>>
>> Yes. The worst that can happen is that Dovecot doesn't see external 
>> changes for 2 seconds. And that's only if your filesystem doesn't 
>> support sub-second timestamps.
>>
>>  
>>> Are the above right, and can Dovecot use its indexes and caches 
>>> safely with others using the same maildirs?
>>>     
>>
>> Yes. I've only recently added maildir_very_dirty_syncs=yes that 
>> improves performance but makes it work less safely when other 
>> programs modify the maildir.
>>
>> Although there is kind of a potential problem if other programs 
>> modify the maildir without locking. 
>> http://wiki.dovecot.org/MailboxFormat/Maildir#Locking but that isn't 
>> unique to Dovecot. That would cause problems with all programs 
>> accessing maildir. Dovecot just logs an error about it, instead of 
>> silently giving broken information to IMAP clients.
>>   
> We have the exact same configuration, and we had similar concerns.  
> I'm happy to say that we (so far) have been pleasantly surprised by 
> how well Dovecot handles this situation and keeps its index files in 
> synch while other 3rd parties (web, etc.) are changing the Maildirs.  
> It seems very reliable, and we haven't seen any problems.
Great to hear that, thanks for sharing!