Mail replies do not use the receiving address as the reply from address When I reply to a mail message, the reply is sent using the default email address as defined in mail.app, and not the email address that it was originally addressed to.

I have all accounts correctly set up and active.

To make it use the correct address, I need to manually select the account I want to send the email through. I am using OS 10.8 recently updated it. It did not happen with previous OS.
This may be because a certain account is locked into a particular SMTP server.


Open Mail Preferences by typing Command + , or Mail -> Preferences
Click the Accounts tab.
Click on an account and make sure "Account Information" is selected.
In the "Outgoing Mail Server" section, make sure the "Use only this server" is not checked.
Do this for every account.