synchronize sent mail between two mailbox

[kilg]

i need to create clone of same mailboxes.
example: user@domain and user.clone@domain
all incoming mail in user@domain i can forward to user.clone, but how can i synchronized sent mail?
i had idea to mount sent folder from user to user.clone, but if user will delete massage by mistake user.clone lost this too.
its very important to save all mail

[phoenix]

Search the forums and wiki for "always_bcc" or "legal intercept".

[kilg]

Search the forums and wiki for "always_bcc" or "legal intercept".

both this method sent intercept mail to target from Postmaster with attached letter.
it is very uncomfortably if I want to find particular mail.
no way to put this intercept mail to folder sent and not attached automatically?