kmail - tie identity to recipient

Is there any way to tie the sender's identity to the recipient in kmail? For 
instance, I use a different identity, with its associated signature and reply-
to address, when emailing family members from the one used when emailing a 
mailing list. Is there any way of automating the tie-up?  I realise that it's 
possible to email from a particular folder and have the identity selected, but 
I can't see how to do it if I'm simply choosing a recipient from the address 
book or entering the email address manually.
 
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John

[email protected]