Postfix is a very popular MTA on unix systems and there is a good chance you are using it. If so, it is very easy to set it up to BCC all emails to MagicBell. Add this to the /etc/postfix/main.cf file
always_bcc = firstname.lastname@example.org
You can also setup postfix to only bcc for specific senders or recipients
sender_bcc_maps = hash:/etc/postfix/sender_bccrecipient_bcc_maps = hash:/etc/postfix/recipient_bcc
This step requires you to use the postmap command to generate the indexed maps. There is more information and some examples in this blog post.