Hello,

there is the following conversion:
EHLO/STARTTLS/EHLO/MAIL FROM
>>> 250 2.1.0 <snip>... Sender ok
<<< RCPT To:<snip>
>>> 451 4.7.1 Please try again later
<<< DATA
>>> 503 5.5.1 Incorrect command sequence
<<< RSET
>>> 250 2.0.0 Reset state
<<< RSET
>>> 421 4.0.0 Tarpitting active for [me]

Besides other things the server's admin critics falsely(*), he
questions the sequence of two RSETs in a row.
I (client) run sendmail v8.12.3.

Why is sendmail issuing the two RSET commands?
Altough it looks RFC conform - it is not forbidden - but why?

Regards, ska

(*) The "503 5.5.1 Incorrect command sequence" stems from an improper
reject of the DATA in PIPELINING mode, though, it should just have
another code.

"ska" <skg@mail.inf.fh-brs.de> writes:

> Hello,
>
> there is the following conversion:
> EHLO/STARTTLS/EHLO/MAIL FROM
>>>> 250 2.1.0 <snip>... Sender ok
> <<< RCPT To:<snip>
>>>> 451 4.7.1 Please try again later
> <<< DATA
>>>> 503 5.5.1 Incorrect command sequence
> <<< RSET
>>>> 250 2.0.0 Reset state
> <<< RSET
>>>> 421 4.0.0 Tarpitting active for [me]
>
> Besides other things the server's admin critics falsely(*), he
> questions the sequence of two RSETs in a row.
> I (client) run sendmail v8.12.3.
>
> Why is sendmail issuing the two RSET commands?
> Altough it looks RFC conform - it is not forbidden - but why?
>
> Regards, ska
>
> (*) The "503 5.5.1 Incorrect command sequence" stems from an improper
> reject of the DATA in PIPELINING mode, though, it should just have
> another code.

Sendmail may issue RSET to check in SMTP connection stored in connection
cache is "usable". Could you post such conversation *with* time stamps?

--
[pl>en: Andrew] Andrzej Adam Filip : anfi@priv.onet.pl : anfi@xl.wp.pl
Before You Ask: http://anfi.homeunix.net/sendmail/B4UAsk-Sendmail.html
http://anfi.homeunix.net/sendmail/

> > there is the following conversion:
> > EHLO/STARTTLS/EHLO/MAIL FROM
> >>>> 250 2.1.0 <snip>... Sender ok
> > <<< RCPT To:<snip>
> >>>> 451 4.7.1 Please try again later
> > <<< DATA
> >>>> 503 5.5.1 Incorrect command sequence
> > <<< RSET
> >>>> 250 2.0.0 Reset state
> > <<< RSET
> >>>> 421 4.0.0 Tarpitting active for [me]

> Sendmail may issue RSET to check in SMTP connection stored in connection
> cache is "usable". Could you post such conversation *with* time stamps?

00:03:30 <<< MAIL From:
00:03:36 >>> 250 2.1.0
00:03:36 <<< RCPT To:
00:03:36 >>> 451 4.7.1
00:03:36 <<< DATA
00:03:36 >>> 503 5.5.1
00:03:36 <<< RSET
00:03:36 >>> 250 2.0.0 Reset state
00:03:44 <<< RSET
00:03:44 >>> 421 4.0.0

The probability that more than one message waited for deliviery at this
particular time is nearly 100%, so sendmail could go on to the next
message after the first RSET, right? However, we have only one user
forwarding mails to this provider, so maybe sendmail figured that out
and didn't tried the other mails of the same destination address.

I cannot test this behavior further, because after requesting infos
from the postmaster of that server by the user and myself our server
was whitelisted on that gateway. I'm just curious, why the second RSET
got sent.

Bye,