Email generated from clicking a link defaults to one email address and I can't change it

Hello,

  When I click a link that generates an email thread like a "contact us" link on a web page it opens outlook with a message ready to send with no body.  This message will be sent from my personal email address and I cannot change it even though my outlook is setup to receive and send emails from 2 work emails and 2 personals.  Is there a way to choose which email address is being used for an auto generated message or do you have to close it and manually create it by copy and pasting the email address the link generates (this is how I have bypassed it)?