PURPOSE
When displaying an email in a list the mail client (gmail, outlook...) computes
a preview based on the content. This preview is generally not well computed as
it contains a lot of garbage and tags while it should contain only relevant
text.
SPECIFICATIONS
To build this preview, all mail clients read the content of the email.
The only way to be able to customize the preview is to add an invisible
HTML element at the beginning of the email with the wanted preview text.
We add at the end of the preview `‌` (zero-width non-joiner) to
fill the end of the preview in order to not have the beginning of the
mail at the end of the preview. It doesn't work with simple space as
the mail clients trim each HTML element content.
Task ID-2172125
PR #49886