I have started on -01 draft.
- XML corrections so that the XML2RFC TXT conversion (some figures,
list, line spacing) is laid out correctly.
- Added text to background section paragraph highlighting the fact the
proposed SMTP extension does not change RFC5321 due to the fact
Greylisting and MTA specific retry strategies are already out of scope.
- Added to section 3.1 SMTP Client/Server Implementation
SHOULD|MAY|MUST [NOT] semantics. This will need review to get right.
- A consideration to simplify Servers implementation of the retry=time
tag where the server blocking time is already known in seconds and
would be an easier text response change is replace the text word to
"retry=seconds" compared to calculated the time in a HH:MM:SS format.
If considered, I think the ABNF change would be:
retrytime = ("retry=" [days "-"] hours ":" minutes ":" seconds) /
days = 2DIGIT ; 00-99
hours = 2DIGIT ; 00-23
minutes = 2DIGIT ; 00-59
seconds = 2DIGIT ; 00-59
totalsecs = 1*(%d48-57) ; total seconds to delay
If this suggestion for a 2nd syntax format is acceptable, is the ABNF
An SMTP Extension I-D was posted
Title : SMTP Service Extension for Greylisting Operations
Author(s) : Hector Santos
Filename : draft-santos-smtpgrey-00.txt
Pages : 17
Date : 2011-10-23
GREYLIST is a SMTP extension to formalize the widely supported
Greylisting mail filtering method and to help support SMTP rejected
transports by following a new formal structured 4yz server temporary
rejection response by including a retry=time tag string which SMTP
clients can use to optimize the rescheduling of the mail delivery
attempts. With adoption, network overhead reduction in wasteful mail
delivery attempts will be realized.
I would like to thank all the people who provided guidance in producing
this initial draft. Much obliged. It is far from done so all input and
considerations from large, small to mom and pop people would be greatly
Our mail servers have already implemented the SMTP extension so if you
need a test site, you can send mail to:
If I have written to you in the past privately, you are probably already
auto white listed. So use an different sender account if you are
interested in testing the server with its 45x greylist responses that
now include the proposed retry=time hint information.
In addition, if you are exploring the proposal for your own Greylist
server implementation, provide the address info so we can run test as well.