Most likely yes, but there are several ways:
1) you could set up your custom email database as a mail-in database, with its own address
2) you could create a Rule in your own database that selects and forwards mails
3) or an agent that forwards mails
What's important:
- where does the mail come from?
- what is it addressed to?
- if it's addressed to you, how can one determine if mail is for you or for the custom mail db?