Milter-greylist

Tere.

Postfix includes good helo check options 
(http://www.postfix.org/uce.html#smtpd_helo_restrictions):

smtpd_helo_restrictions = reject_non_fqdn_hostname, 
reject_invalid_hostname, reject_unknown_hostname

And sendmail does not, which is sad as this is quite efficient, 
especially when unknown_hostname_reject_code is set to 550.

One way to implement it somehow into sendmail is using milter-regex 
(http://www.benzedrine.cx/milter-regex.html), but as this is again 
another milter and as milter-greylist also includes regular expressions 
support, then maybe is possible to to add invalid helo strings check 
directly into milter-greylist?

-- 
Mart