[Mimedefang] Rejecting Mails for More Than 3 Unknown Users

[imacat]

Dear all,

    Hi.  This is imacat from Taiwan.  Is it possible to reject mails for
more than 3 unknown users, to fight against dictionary attacks?

    I have thought about this in 2 ways,

     1. In filter_recipient(), if there are already 3 unknown recipients,
drop all the following recipients.

     2. In case of a mail got through because a valid user is the first
one in 20 tries, in filter_begin() check that more than 3 recipients are
rejected and reject this mail.

    How can I implement this, i.e., keep track of the number of
recipients rejected between RCPT TO commands?

-- 
imacat ^_*'
imacat at mail.imacat.idv.tw
PGP Key: http://www.imacat.idv.tw/me/pgpkey.txt

Tavern IMACAT's http://www.imacat.idv.tw/
Woman's Voice http://www.wov.idv.tw/
TLUG List Manager http://www.linux.org.tw/mailman/listinfo/tlug
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 195 bytes
Desc: not available
URL: <https://lists.mimedefang.org/pipermail/mimedefang_lists.mimedefang.org/attachments/20070327/db8efb3f/attachment.sig>