[Dovecot] dspam integration

[Peter Fern]

Johannes Berg wrote:
>> Another problem is waiting for dspam child process exit, so IMAP
>> session is blocked. Why not to fork and forget dspam child process?
>>     
>
> Because we need to know whether it liked us?
>   

But it's slow.  Especially with bulk moves - I had users complain about 
this so often that I ended up moving to DMT style batch processing using 
the code here:

http://members.plug.org.au/~linuxalien/dokuwiki/projects:dovecot-mysql-dspam-plugin

Users are happy - it's fast, and let's be honest - the majority of users 
really don't care if there's some transient error with the spam 
classifier, they just find it confusing.  And if there are errors, you 
can have them reported by the daemon or cron job that processes the 
batch data.