By entering your email address, you will be able to send email from your browser. You need to enter your email address and mail server name.
Without the server name, you can send a message, but you will not be able to receive a response because your email address will be unknown.
Ask your family to check the setting.
Examples:

In your browser, find the Mail Preferences menu item. (the name may be different depending on the browser)

In the menu, enter your email address and the mail server name.