Hello Amlan,
Could you please share your remote delivery configuration in
mailetcontainer.xml? Have you been configuring it as a SMTP gateway?
I noticed this too in a performance enhancement session with flame
graphs. To be fairly honest the code paths handling direct resolution
and gateway resolution are relying on the very same code path,
preventing efforts to pool the underlying SMTP transports and do
effectively connection pooling.
I think this could be achieved by segregating the two use cases and
actually write two transport layers (both relying on javax.mail), one
doing just direct resolution with connection churn, one achieving
gateway forward with good connection pooling.
Also with gateway mode turned on, we no longer need per-domain delivery
and can group deliveries (this would reduce network exchanges /
connection overhead).
We can discuss those more these technical details. I would personally
more than welcome contribution on the topic of "Outgoing SMTP connection
reuse when gateway mode is active". I would also be happy to be
sponsored to contribute it.
Cheers,
Benoit
On 13/07/2021 16:18, Amlan Sengupta wrote:
> Hello,
>
> We are seeing something very strange with Apache James MTA.
>
> Keeping the flow below in context, we have a client which only uses 1
> connection ad reuses it send emails to Apache James. We have confirmed this
> through connection tracking. We are seeing Apache James spawning up to 60
> connections.
>
> Flow :
> Docker Client ---- ( 1 connection : 60 emails ) ----> Apache James ( MTA ) on
> Docker ---( spawning 60 new connections ) -> SMTP Gateway.
>
> Configuration:
> I have sent the following to 1 and retested. It still behaves the same way.
>
> MTA_SPOOL_THREADS=1
> MTA_DELIVERY_THREADS=1
>
>
> <!-- Number of spool threads -->
>
> <spooler>
>
> <threads>${env:MTA_SPOOL_THREADS}</threads>
>
>
> <errorRepository>file:///deployments/logs/mail/error/</errorRepository>
>
> </spooler>
>
> <!-- The number of threads that should be trying to deliver outgoing messages
> -->
> <deliveryThreads>${env:MTA_DELIVERY_THREADS}</deliveryThreads>
>
>
> Objective here is limit the no of connections made to SMTPGateway.
>
> Any guidance ? Amlan
>
>
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