Which Chrome extension enables sending postal mail through Gmail?
This one is good. https://chrome.google.com/webstore/detail/send-from-gmail-by-google/pgphcomnlaojlmmcjmiddhdapjpbgeoc?hl=en
Your answer is not what is asked
What exactly are you after? Are you looking for a service that allows you to send an email, have it printed out and delivered as snail mail, or something else?
Yes precisely what you understood