When sending email from an application (for example during user registration, booking confirmation, and account alerts), is it important to also send a plain text version?
My understanding is that plain text email was popular among users in the years past since it used less bandwidth and was therefore faster to load on slow internet connections. Therefore all important email communication was sent out in a plain text version (along with the HTML version).
When sending important emails to users in 2021, is it still recommended to also send a copy in plain text?
Note: an easy answer would be "yes", simply because it's the safest thing to do. But I wonder if any users these days lack the bandwidth to download and read an HTML email? And therefore is the plain text version really necessary?