[Mimedefang] Question about mail/expn/vrfy/etrn

[Lucas Albers]

Under what conditions would a mail server not send the following commands
on a connection?
(Assuming I am talking about sendmail.)

ex:
s32.iglobalcommunications.com [64.143.184.32] did not issue
MAIL/EXPN/VRFY/ETRN during connection to MTA

Would it be normal to expect all connecting mail servers to send either
helo or ehlo?

I was under the assumption that the mail server has to receive this
command at the very least to accept mail.

(See below for actual sendmail.mc line.)


Would it be worthwhile to block mail based on the absence of these headers?

I remember their was a setting in sendmail, needmailhelo.
I currently have this line in my sendmail.mc file:
define(`confPRIVACY_FLAGS', `noverb, authwarnings,restrictmailq,
restrictqrun, goaway, noexpn, noreceipts, authwarnings,
noreceipts,novrfy,noexpn, noetrn')

And I used to have this line:

define(`confPRIVACY_FLAGS', `needmailhelo
authwarnings,novrfy,noexpn,restrictqrun,')dnlsed to have a line with:

I kept runnng into problems with integrated mail servers not sending helo.
So I turned it off.
I couldn't find a line that checked to see if it had received ehlo.

I was under the assumption that you have to receive either a ehlo or helo
at some point in the transaction.



Does anyone else filter on helo/ehelo command and had problems with valid
mail servers not sending the command?
Have you been catching a lot of spam using this method?
An irrelevant question if your fp rate is too high.

It might be reasonable to implement as a sa check.

--Luke