I have my enjin mail editor set to the "BBCode mode" by default, as I prefer it over the visual editor.
However, there has been a bug with this since very early on, so I wanted to see if this was on radar for a fix at any point. I often compose messages in other notetaking apps, before trying to copy/paste the message into the browser editor. But when I try to paste in BBCode mode, the editor doesn't recognize my tap or tap-hold and therefore the contextual menu to paste does not pop up.
I am using iOS, but the issue is present in both the default Safari browser and the Google Chrome browser.