As explained in the public docs:

• Change how emails are processed across service projects 

as a Jira administrator after you set up your email channel, you can change how emails are read, view logs, or check the email connection for any email channel on the whole site.

As different service projects might have different requirements it'd be useful to be able to configure the following settings:

• Strip quotes — choose whether emailed comments contain the entire email thread, or just the most recent reply.

• HTML email parsing — choose whether HTML emails display in wiki markup or plain text.

behavior as well per service projects and not only for the settings to be applied to the whole site.