[Dovecot] writing a plugin for LDA to chain Unix pipes

[John Peacock]

martin f krafft wrote:
>> `dspam --stdout| dovecot-lda -d $u`
>> or
>> `spamassasin | custom filter| dovecot-lda`
> 
> I read somewhere on the net that this is pretty flakey and will fail
> badly in the case of intermittent errors, but I cannot find the
> reference anymore. Is anyone using this with success?

I'm using the former mode (with vpopmail) for dspam scanning at the domain level
and it works fine.  The only issue I know of with the above is if the first
command in the pipe dumps core, then no error will be propagated back and the
message will be lost without trace.

> Also, the above spawns an expensive shell process, doesn't it?

At that point in the delivery process, everything is asynchronous (meaning the
queue can handle each delivery at whatever rate it wants to without slowing down
accepting mail), so it really doesn't matter whether spawning a shell is a
performance drag.

Besides, dspam is very resource intensive (as is spamassassin) so the addition
of a shell process is truly immaterial...

John

-- 
John Peacock
Director of Information Research and Technology
Rowman & Littlefield Publishing Group
4501 Forbes Blvd
Suite H
Lanham, MD 20706
301-459-3366 x.5010
fax 301-429-5747