SMTP connection very slow

[Eric]

Hi All,

I am a newbie to sendmail and need some help.

Currently, connections to the sendmail (8.14.3) SMTP port is very slow.

I have already set Ident Timeout to 0.

My observation is that the slowness is due to sendmail performing a
reverse/forward DNS lookup on the source IP of the connection, and the
source IP is not resolvable.

Is there any way we can disable the reverse/ forward lookup on sendmail? In
my case, setting a private DNS or Host file is not practical, as there are
many possible source IPs and they are not fixed.

Thanks a lot.
Eric

[Stampel]

Hi Eric,

Do you try using a timeout option in your DNS search /etc/resolv.conf ?

"Eric" <draco...@hotmail.com> a écrit dans le message de
news:glkqkk$j1a$1...@reader01.singnet.com.sg...

[D. Stussy]

"Eric" <draco...@hotmail.com> wrote in message
news:glkqkk$j1a$1...@reader01.singnet.com.sg...

... And the problem is, what?

Requiring a reverse lookup and forward lookup verification is a good spam
blocker all by itself. If you are dealing with some address that doesn't
have a hostname linked to it, then the administrator of that system isn't
following BCP and needs to be shot, drawn, and quartered. Since the
connection is going to get killed and is not viable, does any delay really
matter? Chances are you're not getting DOS'ed by a flood of useless
connections (in which case, there are better solutions).

[Eric]

Thanks for the suggestion. Yup. It has already been set to 2 sec previously.

However, we still experience about 10-15 sec of delay during initial
connection, and about 5 sec delay for subsequent connection...

Thanks.

Eric

"Stampel" <nos...@01si.com> wrote in message
news:497eef65$0$18769$426a...@news.free.fr...

[Eric]

Hi Stussy,

Thanks for the reply.

In our scenario, we do not mean for this sendmail to serve as a public mail
relay. In fact, this sendmail that I am configuring will only be used for
direct connection from the various client entities, and will not be listed
in MX. We just want to make use of the SMTP protocol to transfer our data.

ie The mail clients will configure their "outgoing SMTP server" to point
directly to this sendmail. (No routing via any intermediate relay is
necessary)

As such, it is not really mandatory for the IP to be registered in DNS in
our scenario.

I know there might be other better protocol to trasfer data, ie FTP/SCP etc,
but as I am stuck with SMTP and sendmail, is there any configuration
parameters in sendmail.conf that I can change to disable the behaviour?

Thanks in advance.
Eric

"D. Stussy" <sp...@bde-arc.ampr.org> wrote in message
news:glns2a$kiq$1...@snarked.org...

[D. Stussy]

"Eric" <draco...@hotmail.com> wrote in message

news:gloc4u$l06$1...@reader01.singnet.com.sg...
> Hi Stussy,

Try addressing me PROPERLY.

> Thanks for the reply.
>
> In our scenario, we do not mean for this sendmail to serve as a public
mail
> relay. In fact, this sendmail that I am configuring will only be used for
> direct connection from the various client entities, and will not be
listed
> in MX. We just want to make use of the SMTP protocol to transfer our
data.
>
> ie The mail clients will configure their "outgoing SMTP server" to point
> directly to this sendmail. (No routing via any intermediate relay is
> necessary)
>
> As such, it is not really mandatory for the IP to be registered in DNS in
> our scenario.

So? Register it in your INTERNAL DNS...

[Eric]

Hi D. Stussy,

Apologies for not addressing you properly in my previous post.

Guess I am back to square one then. We will not be able to remove the delay
by tweaking the behaviour of sendmail.

Thanks.
Eric

Guess there is

"D. Stussy" <sp...@bde-arc.ampr.org> wrote in message

news:glp2q3$ojf$1...@snarked.org...