When inviting existing user to a topic/message, the email notifications are strange … the text version says:
invitingusername invited you to a topic 'Example Topic' on My Discourse Site: Please visit this link to view the topic: https://discourse.example.com/t/example-topic/42/1 To unsubscribe from these emails, visit your [user preferences](https://discourse.example.com/my/preferences).
The HTML version is only the standard notification style with no additional context, i.e.:
poster Posting User
Hi, here’s my example message!
To respond, visit https://discourse.example.com/t/example-topic/42/1 in your browser.
To unsubscribe from these emails, visit your user preferences.