How you can access the HTML of an email you sent from HubSpot

Go to Marketing > Email in your HubSpot account.
Click on the name of the sent email.
Hover the preview of your email under your email name, and click View email. This will open a web version of your email in the browser.
Right-click on the page to view the raw HTML of your email, then select View Page Source.
Highlight the content on the page, right-click, then select Copy to copy email's HTML to the clipboard.