I am redesigning my company's email templates and I opted to code the basic structure from scratch rather than wrestling with what has been created in the distant past.
I ran into a problem designing the footer when I started testing the email in multiple mail apps. In researching the best way to fix it, I stumbled upon the factoid that you should design emails with table-based layouts. I was rather surprised as table-based layouts have been out of date for years.
In 2019 are tables still the go-to method for designing email templates in HTML?
Sources: https://templates.mailchimp.com/getting-started/html-email-basics/ https://www.campaignmonitor.com/blog/email-marketing/2019/04/tables-in-html-emails-nesting/
Based on all of my experience with responsive emails, yes, they are still the way to go. There are frameworks to help with the process of creating the layouts though.
Check out:
https://mjml.io/
https://foundation.zurb.com/emails/email-templates.html
There are others, but I've played around with both of these.