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Re: [ietf-smtp] Per-Recipient Data Responses

2014-03-05 13:26:31

thanks for bringing this issue to our attention.

For the receiving MTA side, I have written a tool, that builds on the Milter interface in sendmail/postfix and provides API for other plugins, that can decide per recipient, if s/he wants to receive the message.

Basically, the module that decides per recipient evaluates Sieve scripts (src/modules/mod_sieve) after RCPT and DATA-DOT and rejects the message. To build the Sieve module, you need either to install the libcyrus_sieve from the development version of cyrus-imap (once you compile the project, you need to install the libcyrus, libcyrus_min and libcyrus_sieve libraries), or libsieve (

The only reason I have not released the software so far, is that it lacks documentation.

Some years ago I managed to tweak sendmail to accept the PRDR parameter to the MAIL command and then it acted correctly (to the extend I understood PRDR).

Recently I switched my programme from C to C++ and have not tested yet, with the sendmail patches from that time, if the PRDR stuff is running.

However, I would be glad if somebody contributes to Sendmail to extend the milter-side/API, so that one can send over it arbitrary responses after data-end and my milter just uses that API instead of me trying to hack sendmail.

Next to that, I intend to write documentation for the above programme, so that more people can use it. I would be very happy, if somebody is interested to help me.

Per recipient response is very cool, as each recipient in the same mail envelope can have different spam rules and PRDR provides the possibility to only partially reject the message. Also, if the recipient agree, in the rejection message one can write the telephone/fax number of the recipient, so that the sender can still contact the recipient, if was wrongly rejected.


On 05.03.2014 19:20, Murray S. Kucherawy wrote:
How come this never got adoption?  It comes up from time to time in "We
really should do this" sorts of discussions, but it doesn't seem like
anyone ever took the plunge and it just expired.  Is it just that nobody
does it because nobody else does it?


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