If you've used the new email designer export email functionality, you'll know that it's unusable. If you haven't used it, it generates a zip file with a HTML file inside. The HTML file contains the raw markup/syntax and is completely useless for sharing or collaborating.
Here's a the bookmark for your Chrome browser, based on the original email editor 2.0 version, to download the HTML from the simulate content UI.
javascript:(function()%7Bif%20(window.location.hostname.indexOf(%27experience.adobe.com%27)%20%3D%3D%20-1)%20return%20alert(%27Ensure%20you%20are%20logged%20into%20Adobe%20Marketo%20Engage%27)%3Blet%20a%20%3D%20null%3Blet%20b%20%3D%20document.querySelector(%27div%5Bdata-testid%3D%22emailSubject%22%5D%27)%3F.textContent%3Bconst%20c%20%3D%20%5B...document.querySelectorAll(%22iframe%22)%5D%3Bif%20(c.length)%20%7Bdo%20%7Bconst%20d%20%3D%20c.pop()%3Bif%20(d.getAttribute(%22data-testid%22)%20%3D%3D%3D%20%22emailDesignerPreview%22)%20%7Ba%20%3D%20d%3Bbreak%3B%7Dtry%20%7Bconst%20e%20%3D%20d.contentDocument%20%7C%7C%20d.contentWindow%3F.document%3Bif%20(e)%20%7Bc.push(...e.querySelectorAll(%22iframe%22))%3Bif(typeof%20b%20%3D%3D%20%22undefined%22)%20b%20%3D%20e.querySelector(%27div%5Bdata-testid%3D%22emailSubject%22%5D%27)%3F.textContent%3B%7D%7D%20catch%20(err)%20%7B%7D%7D%20while%20(c.length%20%3E%200)%3B%7Dif(a%20%3D%3D%3D%20null)%20return%20alert(%27Could%20not%20find%20target.%20Please%20open%20a%20Marketo%20email%20in%20simulate%20content%20to%20download%20HTML%27)%3Bconst%20f%20%3D%20a.contentDocument.getElementsByTagName(%27html%27)%5B0%5D.outerHTML%2Cg%20%3D%20new%20DOMParser()%2Ch%20%3D%20g.parseFromString(f%2C%20%27text%2Fhtml%27)%2Ci%20%3D%20h.querySelectorAll(%27script%27)%2Cj%20%3D%20h.querySelectorAll(%27a%27)%3Bi.forEach(el%20%3D%3E%20el.remove())%3Bj.forEach(el%20%3D%3E%20%7Bif(el.hasAttribute(%27_href%27))%20el.setAttribute(%27href%27%2C%20el.getAttribute(%27_href%27))%7D)%3Bconst%20k%20%3D%20h.documentElement.outerHTML%3Blet%20l%20%3D%20document.createElement(%27a%27)%3Bl.download%20%3D%20new%20Date().toISOString().split(%27.%27)%5B0%5D.replaceAll(%2F%5B-%7CT%7C%3A%5D%2Fgi%2C%27%27)%20%2B%20%22_%22%20%2B%20b.replace(%2F%5B%5EA-Za-z0-9%5D%2Fg%2C%20%27_%27)%20%2B%20%22.html%22%3Bl.href%20%3D%20%22data%3Atext%2Fplain%2C%22%20%2B%20encodeURIComponent(k)%3Bl.click()%3B%7D).call(this)%3B%3Bvoid(0)%3B
Instructions: just add a new bookmark and copy & paste the whole chunk above into the URL then click the bookmark button when viewing a New Email Designer email in simulate content
Check out v2 of the email editor 2.0 bookmark here