OT Sendmail configuration question

JD jd at BENTECMED.COM
Tue Feb 15 18:33:04 GMT 2005


Does creating a delay in the 220 greeting really make any difference in your
experience? Im wondering if I shouldupgrade to 8.13 to try it out.

-JD

-----Original Message-----
From: MailScanner mailing list [mailto:MAILSCANNER at JISCMAIL.AC.UK]On
Behalf Of John Rudd
Sent: Friday, February 11, 2005 9:02 PM
To: MAILSCANNER at JISCMAIL.AC.UK
Subject: Re: OT Sendmail configuration question


No, milters don't happen until later in the conversation (as far as I
know), so I don't think milters can do it.  It required new code, so
I'm pretty sure you really need to use 8.13 and not 8.12.  But, 8.13.1
is pretty rock solid.  I can't think of a reason NOT to upgrade to it
from 8.12.

On Feb 11, 2005, at 5:49 PM, Alex Neuman van der Hans wrote:

> There is *no* way to do this on sendmail 8.12, is there? Maybe through
> a
> milter? Just asking, not intended as flamebait (you know, people
> screaming
> RTFM and the like)...
>
> -----Original Message-----
> From: MailScanner mailing list [mailto:MAILSCANNER at JISCMAIL.AC.UK] On
> Behalf
> Of John Rudd
> Sent: Friday, February 11, 2005 6:33 PM
> To: MAILSCANNER at JISCMAIL.AC.UK
> Subject: Re: OT Sendmail configuration question
>
> 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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