FileMaker Pro has built in and scriptable "send email" functions, which you can perform from filemaker, then it will create email messages to send from Outlook, but you may want to check compatibility issues with different email versions and FileMaker versions:
Specifically which fields in Outlook are you wanting to automatically populate with data from your FM database? Just To, CC, and Subject or do you need to populate the body of the message as well?
Also, are you wanting FM to (virtually) hit the SEND button too?
One last thing; are you operating in an Exchange environment?