If you are using Gmail as an email client, you will need to authenticate your account before you grant permission to another user to send on your behalf.
To get this started, under the Track tab, you’ll see the “Send on Behalf of” section, you’ll want to click “Authenticate”.
You’ll be taken a Google page where you’ll need to click “Allow”. In order for this to work, the email address in the corner of the page will have to match the email address you use to login to Entelo.
Lastly, you’ll need to go back to your settings and choose the person you want to grant access to from the dropdown. They will then be able to choose your name and email from the 'From' field when composing a message.