[Dovecot] LDA vs. LMTP

Stan Hoeppner stan at hardwarefreak.com
Tue Jul 30 00:32:40 EEST 2013

On 7/29/2013 2:30 AM, Jan Behrend wrote:

> You cannot use the LDA method if SMTP and IMAP services reside on
> different machines, which would be the case in larger scale mail system
> setups.

Which brings up an interesting point.  With a single LMTP daemon on the
Dovecot server communicating via a single socket with the upstream MTA
over the wire, it would stand to reason that message throughput rate may
be limited by serialization in the LMTP request/reply chain.  There is
no parallelism, and thus there is relatively high latency.

In the case of LDA with an SMTP MTA on the local box, the potential
exists for very high parallelism, and thus elimination of the latency in
serial delivery over a single socket with LMTP.

So in theory, while LDA in this scenario would consume far more
resources with a very high message load, one should be able to attain
much higher message throughput.  I say in theory because I've not tested
this head to head.


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