There are many things you can implement into your HTML to ensure your emails are available to as many of your recipients as possible. Think about things you can do to reduce barriers for them, as well as the tools (such as screen readers) they might be using to read your emails. Below are a few things you can use as a checklist when creating your template, the more you implement into your HTML, the more accessible your emails will be.
There are many things that need to be tested before an email is sent out, however testing during the build stage is also just as important. Your Design System will be the base for all emails created from it, so making sure the code is supported in as many email clients as possible and renders correctly on desktop and mobile, is something that should happen throughout the build.
There are going to be many elements that make up your Design System, which means you will want to think about running quick tests, for when a new element or section of the code is added, and doing more frequent in depth testing for seeing how your code is rendering in different email clients and devices. By doing so, you will reduce time spent building the Design System overall because any issues will be caught early and throughout the build, instead of waiting to check at the end.
A few things to look out for while testing: