Concurrent connections

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Concurrent connections

Jeff-266
What settings control how many concurrent connections are opened and the
number of recipients in a single smtp connection when sending mail? (We
send a newsletter to domains all over the world that is accepted by
almost everyone but Yahoo, who defers our mail. That, of course, is
off-topic, but any advice or insight would be greatly appreciated. )
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Re: Concurrent connections

Victor Duchovni
On Sat, Jun 28, 2008 at 10:23:07PM -0400, Jeff wrote:

> What settings control how many concurrent connections are opened

    http://www.postfix.org/postconf.5.html#default_process_limit
    http://www.postfix.org/master.5.html
    http://www.postfix.org/postconf.5.html#default_destination_concurrency_limit
    http://www.postfix.org/postconf.5.html#smtp_destination_concurrency_limit

> and the number of recipients in a single smtp connection when sending mail?

    http://www.postfix.org/postconf.5.html#default_destination_recipient_limit
    http://www.postfix.org/postconf.5.html#smtp_destination_recipient_limit

--
        Viktor.

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Re: Concurrent connections

Ralf Hildebrandt
In reply to this post by Jeff-266
* Jeff <[hidden email]>:

> What settings control how many concurrent connections are opened and the  
> number of recipients in a single smtp connection when sending mail?

Obviously just ONE concurrent connection is opened in a single smtp
connection :)

--
Ralf Hildebrandt ([hidden email])          [hidden email]
Postfix - Einrichtung, Betrieb und Wartung       Tel. +49 (0)30-450 570-155
http://www.arschkrebs.de
Cogito ergo dim sum. (I think, therefore these are pork buns.)
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Re: Concurrent connections

Frederick Isaac
Ralf,

Actually that is not obvious at all.
It might be obvious that one concurrent connection is opened per concurrent host connection.

Cheers




--- On Sat, 6/28/08, Ralf Hildebrandt <[hidden email]> wrote:

> From: Ralf Hildebrandt <[hidden email]>
> Subject: Re: Concurrent connections
> To: [hidden email]
> Date: Saturday, June 28, 2008, 10:59 PM
> * Jeff <[hidden email]>:
>
> > What settings control how many concurrent connections
> are opened and the  
> > number of recipients in a single smtp connection when
> sending mail?
>
> Obviously just ONE concurrent connection is opened in a
> single smtp
> connection :)
>
> --
> Ralf Hildebrandt ([hidden email])        
> [hidden email]
> Postfix - Einrichtung, Betrieb und Wartung       Tel. +49
> (0)30-450 570-155
> http://www.arschkrebs.de
> Cogito ergo dim sum. (I think, therefore these are pork
> buns.)


     
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Re: Concurrent connections

mouss-2
Frederick Isaac wrote:
> Ralf,
>
> Actually that is not obvious at all.
> It might be obvious that one concurrent connection is opened per concurrent host connection.
>  

Outside of maths, one connection is not concurrent :)

It is unclear which subset of the following the OP wants to control:
- the number of recipients in a single smtp transaction.
- the number of smtp transactions in a single connection.
- the total number of connections open at one time
- the number of connections open with a single peer
and for which side:
- server side (smtpd listener)
- client side (smtp client)





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Re: Concurrent connections

Ralf Hildebrandt
* mouss <[hidden email]>:
> Frederick Isaac wrote:
>> Ralf,
>>
>> Actually that is not obvious at all.
>> It might be obvious that one concurrent connection is opened per concurrent host connection.
>>  
>
> Outside of maths, one connection is not concurrent :)

Exactly :)

--
Ralf Hildebrandt ([hidden email])          [hidden email]
Postfix - Einrichtung, Betrieb und Wartung       Tel. +49 (0)30-450 570-155
http://www.arschkrebs.de
People who can make accurate predictions 10 years into the future
typically don't develop software.                     -- Wietse
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Re: Concurrent connections

Jeff-266
In reply to this post by mouss-2
mouss wrote:

> Frederick Isaac wrote:
>> Ralf,
>>
>> Actually that is not obvious at all.
>> It might be obvious that one concurrent connection is opened per
>> concurrent host connection.
>>  
>
> Outside of maths, one connection is not concurrent :)
>
> It is unclear which subset of the following the OP wants to control:
> - the number of recipients in a single smtp transaction.
> - the number of smtp transactions in a single connection.
> - the total number of connections open at one time
> - the number of connections open with a single peer
> and for which side:
> - server side (smtpd listener)
> - client side (smtp client)
>
>
>
>
>
What is the sound of one concurrent connection clapping?

Thanks for the clarification, mouss. I think my biggest concern is that
there are no more than 5 transactions in a single connection when
sending mail out of my box. Victor saw through my mangled question and
sent links to the relevant info.  I'm still a little confused, though,
about what parameter controls this.  In my case, it looks like
smtp_destination_recipient_limit would do it. Is that correct?

The free mail provider in question here will accept no more than 5 mails
in a single connection. Is the Postfix default really 50? Is it possible
to limit it by domain?

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Re: Concurrent connections

Wietse Venema
Jeff:
> The free mail provider in question here will accept no more than 5 mails
> in a single connection. Is the Postfix default really 50? Is it possible
> to limit it by domain?

There is no parameter that specifies the number of mail transactions
per SMTP session.

You can only choose between one or many.

http://www.postfix.org/postconf.5.html#smtp_connection_cache_on_demand

        Wietse
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Re: Concurrent connections

Victor Duchovni
In reply to this post by Jeff-266
On Sun, Jun 29, 2008 at 09:26:06AM -0400, Jeff wrote:

> The free mail provider in question here will accept no more than 5 mails
> in a single connection. Is the Postfix default really 50? Is it possible
> to limit it by domain?

Don't confuse the recipient count limit for a single message with the
number of messages delivered over a single SMTP session. Which are you
trying to limit? The recipient count or the delivery count?

    C: SYN S: SYN-ACK
    C: ACK S: 220
    C: EHLO S: 250
    C: MAIL S: 250
    C: RCPT S: 250 \
    C: ... S: 250  | Up to <transport>_destination_recipient_limit times
    C: RCPT S: 250 /
    C: DATA S: 354
    C: HDRBODY S: ACK
    C: .CRLF S: 250

    C: RSET S: 250
    C: MAIL S: 250
    C: RCPT S: 250 \
    C: ... S: 250  | Up to <transport>_destination_recipient_limit times
    C: RCPT S: 250 /
    C: DATA S: 354
    C: HDRBODY S: ACK
    C: .CRLF S: 250
    C: RSET S: 250

    ... If connection caching is enabled, and there is enough mail in
        the queue, a connection may be re-used for multiple deliveries,
        Postfix limits the total lifetime of cached connections, not the
        number of deliveries. The default limit is 300s, which is comparable
        to the SMTP command timeouts to avoid slow-server "attractors".

    C: RSET S: 250
    C: MAIL S: 250
    C: RCPT S: 250 \
    C: ... S: 250  | Up to <transport>_destination_recipient_limit times
    C: RCPT S: 250 /
    C: DATA S: 354
    C: HDRBODY S: ACK
    C: .CRLF S: 250
    C: QUIT S: 221

--
        Viktor.

Disclaimer: off-list followups get on-list replies or get ignored.
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If my response solves your problem, the best way to thank me is to not
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"It worked, thanks" in the "Subject" so I can delete these quickly.