How do I set up two-factor authentication?

Sign in, find, and hover over your email address in the top right corner.
Click on Settings in the menu that pops up.
Click on the Business Features tab at the top of the page.
Scroll down to 2-Factor Authentication and then click inside the box to enter your mobile phone number, then click Verify. You will then be sent an SMS message with a phone verification code.
You will be prompted to enter your phone verification code. After entering this, click Submit.
If the code matches, you will get a confirmation message that your 2-factor authentication is now active. You will also be given a one-time backup code that you can use just in case you don't have your phone or the authentication message does not reach you. Save this code and keep it in a secure place. Your 2-factor authentication has now been activated and will be valid for 30 days.