Step 1: Open this link in a new tab:
myaccount.google.com/security

Step 2: Sign in to your Gmail account if prompted

Step 3: Scroll down to "2-Step Verification"
(If it says "Off", click it and follow the prompts to turn it on first)

Step 4: Click into 2-Step Verification, scroll to the very bottom

Step 5: Click "App passwords"
(If you don't see it, search "App passwords" in the Google Account search bar)

Step 6: Type a name like "MP Emailer" and click Create

Step 7: Copy the 16-character password that appears (looks like: xxxx xxxx xxxx xxxx)