Use case of keywords in mails

Since 4D 17R5 it becomes possible to add keywords in a mail header:
<code 4D>
$O_Keywords:=New object(“Matrafich”;True;“Gottseidank”;True;“keywordnotinserted”;False)

</code 4D>

In the real life, who, when and where uses keywords?

For example: Spam application add their keywords to tell if a mail is (likely) a spam or not.
Some application add Keywords to tell this mail is made by this application, etc.


et quand utiliser ces variables préfixées en $ quand j’envoie un message:

<code 4D>
$O_Keywords:=New object

// EOM
</code 4D>