With this workflow it is not possible for a multi-recipient SMTP transaction to accept the email for some recipients and reject it for others. Some users might want to reject whatever suspicious emails they receive, rather than storing them in their Junk folder. Other users might want to have the suspicious mails in their junk folders. And a third group of users might want to deliver the message in their Junk folder, but draw the attention of the sender and, by rejecting the message at SMTP level, communicate to the sender that the message was delivered in the Junk folder. When a mail is sent to more than one of the above groups, what can the MTA server do to satisfy all wishes?
SMTP makes such use cases hard to handle. aegee-milter tries to solve this problem.
To the criticizers, stating that there is a prize for solving the shortcomings of SMTP, the answer is that one has to start somewhere, e.g. with email segmentation.
git clone git://mail.aegee.org/aegee-milter or git clone https://mail.aegee.org/cgit/aegee-milter.
There is no bug tracking system.
The Milter API, extracted from Sendmail.