When replying to a mail where one of the recipients is the same as 
your account address this address is omitted from the reply headers. 
While this behaviour is (probably) desireable most of the time it is
not when this address is an alias since all other recipients don't 
receive the mail.

This results in having to methodically check every reply to make 
sure that the recepients are correct - this is extremely tedious
especially once the number of accounts increases. (I use the accounts
to be able to send mail from multiple aliased identities)

Possible solution: When creating a new account allow the user to select
whether they wish this address to be able to sent replies to itself.