Using $forward_method to forward all mail, but retain a copy.

================ Required information ====
- iRedMail version: 0.8.5
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Linux/BSD distribution name and version: CentOS 6.4 64-bit
- Related log if you're reporting an issue:
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Hello,

I'm using $forward_method = 'smtp:[IP_of_Exchange]:25'; to forward all mail that passes spam checks to our exchange server but I would like to retain a copy of the forwarded emails in the local iRedMail user accounts for archival purposes. Can there be a sieve method implemented that would bcc an email to the users iRedmail inbox before forwarding? if not are there any other options?

Thanks in advance!
Luke