Can I choose which email address I want a specific message to be sent from using Outlook? 

YES...you can Send any message from any mail profile that you setup in Outlook.  For example, if you are received a message addressed to webmaster@yourname.com, then you can have your response come from webmaster@yourname.com instead of your personal email address. 

TIP: Make sure that you have already created the mail profile for that address

1.1. Log on to the Internet
2. Open Outlook
3. Create a new message FILE - NEW MESSAGE
4. Before send the message, FILE -
5. Send the message
Can I RESPOND to an email using a specific email address ?
Respond or Reply to the email that you received (as you usually would do)  BUT before pressing the  Send/Receive button go to FILE - SEND USING - choose the email account you want to send the email from  - as shown in step 4 above then press Send/Receive button - as usual