Mail App with 2 Accounts question

I have two Gmail accounts on my Mail app and was wondering if its possible in any way to only let a message be sent to a specific client from one of those accounts. I need to strictly separate my personal and formal accounts and make sure they don't overlap accidentally (as just happened). Help is very much appreciated.

So you have 1 mail client(app), with more than 1 account, which both in turn contain addresses from clients(contacts)?

I believe that if you are to send a mail to a certain client, you need to select the proper account, and if theres any doubt that you are in fact working from the right account, you can verify this, because you will be prompted when you push the send button.

Hope this helped, Ibanezi