Training Bayes on outbound mail

[Dominic Benson]

Hi -

Recently, in order to balance the ham/spam ratio given to sa-learn, I 
have started to pass mail submitted by authenticated users to sa-learn 
--ham.
The thinking here is that users would generally want to receive mail 
that they send, and many messages will either be replies or replied to, 
so this is likely to have a fair amount in common with legitimate mail 
coming in.
The existing bayes training was from auto-learn, on 60k ham and 360k 
spam; since starting to do this, nearly twice as much ham as spam has 
been learned.

I haven't seen any mention of this strategy on-list or on the web, so 
I'm interested in whether (a) anyone else does this, and (b) is there a 
good reason not to do it that I haven't thought of?

The approach, if anyone is interested, is to use an "unseen" Exim router 
to pipe mail to sa-learn --ham using the pipe transport, on the 
condition that an acl_m variable, set for authenticated users in 
acl_check_rcpt, evaluates to true.

Dominic