How to apply a mail template?

Question

Email

There are many sites with the development of mailing templates that offer to then take the code, for example, like here: responsiveemailpatterns.com/patterns/layout/3-equa...
or offer to download an html template like here: www.campaignmonitor.com/templates
But I I can’t figure out how to send a letter with this template later, or is it somehow done not through the mail.ru or gmail.com online client?
Simply inserting the code into the letter does not give anything, the same code is sent.
Please advise how this is done or, if the topic is broad, materials for study.

Answer 1

Read the material for studying on Habré "kamenty" ;-)
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