KMail: How to tie identities to accounts?

Hello, 

I would like to tie identities to certain accounts, so that whenever I am 
writing under a certain identity the mail will go through a previously 
chosen account. Actually I would even like KMail not to let me change 
that from the editor window to prevent mistakes. 

example
I use separate accounts and identities for "normal" e-mails and mailing 
lists but when I hit send KMail always sends mail using the firs account 
and so the post won't reach subscribers-only list. Everytime I have to 
choose the right account from a drop-down list which is annoying. 


-- 
skx.