How to create preliminary text for a letter?

Question

Email

Hello. Tell me how such a thing is implemented.
Let's say there is a letter in the mail.
When entering the list of letters (main gmail or mail.ru - https://e.mail.ru/messages/inbox/) we see this letter
After the subject of the letter, the first lines of the letter are
indicated your greeting or another part of the text
For example, in letters from Eldorado
Here's how to make your text in the preview of the letter (i.e. here https://e.mail.ru/messages/inbox/)
And these are not the first lines of the letter, but your own text
I tried to open the html code, but I did not find anything similar
. There is no such thing in the service headers either.
Tell me, if anyone understands what I mean :)

Answer 1

Usually a preheader is made with "visibility:hidden" or equivalents, for example

<div style="font-size:0px;color:#ffffff;line-height:0px;">
текст прехидера
</div>