OT Sendmail configuration question

John Rudd jrudd at UCSC.EDU
Fri Feb 11 23:32:55 GMT 2005


I think he's actually talking about the server delaying the
pre-HELO/EHLO greeting (the server's 220 greeting).  It's new to
sendmail 8.13.x, and it's called "greet_pause".

What you want to do, is anywhere after your "access_db" declaration in
the mc file, put:

FEATURE(`greet_pause', `30000')dnl

The 30000 is in milliseconds, so that's a 30 second delay.  Note that
there are some side effects if you go higher than 28 seconds (verizon
does "call backs" when accepting email from you, and if they don't get
a valid response in 28 seconds, they give up and reject your message).

Also, you can put entries in your access_db that look like this:

# 220 GreetPause (miliseconds)
#
GreetPause:127.0.0      0
GreetPause:128.114.125  0
GreetPause:128.114      3000
GreetPause:169.233      15000
GreetPause:             30000

These set aside other delays based upon the connecting host.  0 means
"disable the delay".


On Feb 11, 2005, at 14:54, Alex Neuman van der Hans wrote:

> I don't think that's what he means. It's an option in newer sendmail
> versions (8.13 I think) that lets you insert a delay between the HELO
> from
> the client and the OK from the server.
>
> -----Original Message-----
> From: MailScanner mailing list [mailto:MAILSCANNER at JISCMAIL.AC.UK] On
> Behalf
> Of Mark Campbell
> Sent: Friday, February 11, 2005 5:47 PM
> To: MAILSCANNER at JISCMAIL.AC.UK
> Subject: Re: OT Sendmail configuration question
>
> Is this what you're looking for?
>
> During an SMTP conversation, a client introduces itself to a server
> using
> the HELO or EHLO command. The standard does not specify what should be
> said
> here, and many Windows clients in fact use a "bogus"
> name: for instance, the domain name of the destination server.
> Nevertheless, it may sometimes be useful to check the argument to
> HELO/EHLO,
> as many SPAM programs use bogus arguments in a consistent manner.
>
> In a very helpful e-mail, a sendmail maintainer explained to me how
> this
> could be done. The trick is to use delayed macro expansion with the $s
> macro. As the sendmail manual explains, $s is a transient macro: at
> startup,
> when sendmail reads its configuration file, it contains the name of
> the host
> on which sendmail runs, but during an SMTP conversation, it expands
> into the
> hostname supplied by the remote client as the argument to HELO/EHLO. By
> writing $&s, it is possible to delay the expansion of this macro, so
> it is
> expanded only when it is needed; e.g., during Local_check_rcpt.
>
> Consequently, my sendmail.mc file contains a local rule set similar to
> the
> following (note that Local_check_rcpt, if exists, is automatically
> called by
> sendmail at the appropriate stage of processing the envelope):
>
> SLocal_check_rcpt
> R$*                     $: $&s
> Rbogus.domain           $#error $: 550 Spam Forbidden\ ($&s)
> R$*                     $@ OK
>
>
> REF: http://www.vttoth.com/heloehlo.htm
>
> Mark
>
> Mark Campbell
> --
> IT Convergence OS Administrator <mcampbell at itconvergence.com>
>
>
> -----Original Message-----
> From: MailScanner mailing list [mailto:MAILSCANNER at JISCMAIL.AC.UK] On
> Behalf
> Of Jim Dickenson
> Sent: Friday, February 11, 2005 4:48 PM
> To: MAILSCANNER at JISCMAIL.AC.UK
> Subject: OT Sendmail configuration question
>
> Some time ago there was talk on this list about using a relatively new
> option in sendmail. As I recall there is some option that allows one to
> delay the response to a helo or ehlo line. The theory was that spammers
> could not afford to wait when sending messages and they would not wait
> for
> the delay time.
>
> Can someone remind me what the command was.
>
> I tried to search the archive but not knowing exactly what I am
> searching
> for I did not find the past messages.
>
> Thanks,
> --
> Jim Dickenson
> mailto:dickenson at cfmc.com
>
> CfMC
> http://www.cfmc.com/
>
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