You can update the text that's sent to listeners when added in any way. This could be via Zapier, ActiveCampaign automation, MemberVault integration, Thinkific, etc.
In the feed, find the Listeners tab and click the "Edit Invitation Email Text" button.
This opens a popup where you can add text for all listeners to receive in the feed.
This text is plaintext, but paragraphs and emojis are accepted.