It should be considered a best practice to include a <title> tag within the <head> tag of any HTML document, with a value, and email should be no exception.
While the <title> tag may not be required for optimal experience within email applications (although some may use the title tag), the title tag would definitely be something that could be shown within a 'view in browser' experience. Typically the <title> tag is displayed in the browser tag as the page title. This also can be referenced for accessibility purposes (IE Screen readers)
See this article:
https://www.emailonacid.com/blog/article/email-development/email-accessibilty-in-2017/#:~:text=Set an email title,for people using screen readers.
Today it appears we include a <title> tag in the <head> section of email content created with the D&D editor, there is no value.
A way to set the title tag in email content would required to align with that standard.
