[Mailer] Consume a PSR-14 event dispatcher

[chalasr]

Q	A
Feature PR	symfony/symfony#42662
PR author(s)	@derrabus
Merged in	5.4

[derrabus]

The documentation for the mailer does not mention events at all at the moment:

https://symfony.com/doc/current/mailer.html

I think we should change that.

[carsonbot]

Thank you for this issue.
There has not been a lot of activity here for a while. Has this been resolved?

[alamirault]

@derrabus

Events are now mentioned https://symfony.com/doc/current/mailer.html#mailer-events
Do you think we have to add some info ?

[derrabus]

If we had a section on how to use the component stand-alone (without FrameworkBundle integration), maybe. That documentation page explains Mailer from the perspective of a full-stack Symfony app and in that scenario, we cannot replace the event dispatcher.