Assuming you’re using Microsoft Outlook as your email client, you can follow the steps below to prevent it from being your default email program.
1. Open Microsoft Outlook.
2. Click on the File tab.
3. Click Options.
4. In the Options dialog box, click the General tab.
5. Under the section labeled Start up options, clear the check box next to Make Outlook the default program for E-mail, Contacts, and Calendar.
6. Click OK to close the dialog box.