Jeanie:
You will need to go to the Mail menu and select Preferences. Then click on the second icon in the top bar Accounts. Here you will need to change the Incoming Mail Server and Outgoing Mail Server (smtp). To get the exact information go to their website. Take a look at
Quest's support page and browse the topics. Click on the link to setup my Mail account. There is a link to Apple Mail, and then, depending on the email address you have the list the Incoming and Outgoing Mail servers for you. Then call them for help if you have specific questions. They are often quite good at walking you through the setup. Tell them that you are using Apple Mail and they will have an agent who is familiar with Mail help you.
Please do post back if you have further questions.
😉 cornelius