Change which mail application is used to write emails
When you click a button or link to send a new email (for example, in your word processing application), your default mail application will open up with a blank message, ready for you to write. However, if you have more than one mail application installed, the wrong mail application might open up. You can fix this by changing which one is the default email application:
Open the Activities overview and start typing Apps.
Select Settings ▸ Apps from the results. This will open the Apps panel.
Select Default Apps.
Choose which email client you would like to be used by default by changing the Mail option.