[Dovecot] v1.1.rc8 released

Timo Sirainen tss at iki.fi
Tue Jun 3 01:34:43 EEST 2008

On Mon, 2008-06-02 at 23:25 +0100, Ed W wrote:
> Hi
> > 	+ deliver: Added -c parameter to provide path to delivered mail.
> > 	  This allows maildir to save identical mails to multiple recipients
> > 	  using hard links.
> >   
> Funnily enough it was on my todo list to whip up a small perl program to 
> go and scan my maildirs and figure out if this theoretical idea actually 
> amounted to anything. 
> Algorithm would be this:
> Open each message,
> scan for first blank line. 
> SHA the rest of the message, store the SHA in a hash (along with the 
> message size)
> rinse and repeat and see if we end up with any hashes showing count 
> greater than 1...
> This would represent the best case that we could achieve assuming body 
> content fixed and we find some way to manage variable headers.

Somewhat faster way would be to get a list of file sizes first and not
bother checksumming any files which have a unique size.

> Next up is to use a mime parser and SHA each message part.  Same idea, 
> assuming we used some kind of format to store each part individually, 
> how much gain is this really worth in terms of storage (looks tempting 
> up front, condense all those duplicated jokes, etc - however, does it 
> really bear out in practice...). 

This is in my dbox TODO list (not near future though).

> I think MS Exchange only does single instance storage like you describe 
> here with delivery time hardlinking of messages?  Never analysed what 
> that was worth (back when I had an Exchange system to fiddle with...)

No idea about Exchange, but dbmail 2.3 does single instance MIME part

> I have a feeling that gzip compression of files would be worth more than 
> this hardlinking (on many but not all mail systems...)

Or you could use both. zlib plugin already supports this with maildir.
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