Validating an SMTP server

[Jim Popovitch]

On Mon, Sep 7, 2015 at 2:39 PM, Simson Garfinkel <simsong at acm.org> wrote:
> Jim,
>
> Thanks for giving my tester a try.
>
> I'm confused by your comment, though.  I was pretty sure that SMTP commands
> were supposed to be followed by CRLF.
>
> Here's the quote from RFC 2821:
>
> 2.3.7 Lines
>
>    SMTP commands and, unless altered by a service extension, message
>    data, are transmitted in "lines".  Lines consist of zero or more data
>    characters terminated by the sequence ASCII character "CR" (hex value
>    0D) followed immediately by ASCII character "LF" (hex value 0A).
>    This termination sequence is denoted as <CRLF> in this document.
>    Conforming implementations MUST NOT recognize or generate any other
>    character or character sequence as a line terminator.  Limits MAY be
>    imposed on line lengths by servers (see section 4.5.3).
>
>    In addition, the appearance of "bare" "CR" or "LF" characters in text
>    (i.e., either without the other) has a long history of causing
>    problems in mail implementations and applications that use the mail
>    system as a tool.  SMTP client implementations MUST NOT transmit
>    these characters except when they are intended as line terminators
>    and then MUST, as indicated above, transmit them only as a <CRLF>
>    sequence.
>
> https://www.ietf.org/rfc/rfc2821.txt
>

I think the CRLF vs CR debate is older than the Emacs vs Vi debate.
:-)   Others can probably speak better as to which to use, I'll stand
on the sidelines and share with you Wietse's feelings:   :-)

Sep  7 17:04:13 svr2 postfix/smtpd[17157]: improper command pipelining
after HELO from ec2-52-7-167-73.compute-1.amazonaws.com[52.7.167.73]:
HELO TEST\r\nQUIT\r\n
Sep  7 17:04:52 svr2 postfix/smtpd[17157]: improper command pipelining
after HELO from ec2-52-7-167-73.compute-1.amazonaws.com[52.7.167.73]:
HELO TEST\r\nQUIT\r\n
Sep  7 17:18:15 svr2 postfix/smtpd[17634]: improper command pipelining
after HELO from ec2-52-7-167-73.compute-1.amazonaws.com[52.7.167.73]:
HELO TEST\r\nQUIT\r\n
Sep  7 17:21:58 svr2 postfix/smtpd[17871]: improper command pipelining
after HELO from ec2-52-7-167-73.compute-1.amazonaws.com[52.7.167.73]:
HELO TEST\r\nQUIT\r\n

You probably should also get a matching PTR for 52.7.167.73, you can
request that on this form:
https://aws.amazon.com/forms/ec2-email-limit-rdns-request?catalog=true&isauthcode=true
(yes I know it says "Request to Remove Email Sending Limitations", but
it's also for rDNS requests)


-Jim P.