On any grid where the constituent’s email address is shown the email address is a link that you can click on to send an individual email. Depending on your user settings, it will either open the Direct Email window or it will open the default email program set up for your browser. 

Direct email is a feature that allows you send emails from within the software as well as store a record of the email in the constituent's profile record in their Email Marketing tab. You can activate direct mail in your user settings. See this article for more information. https://support.donorview.com/en/support/solutions/articles/9000239283-how-can-i-set-up-direct-mail-