>>Worth bearing in mind that that the use of i (and b) tags is discouraged and should, where possible, be avoided:
>>https://www.w3.org/International/questions/qa-b-and-i-tags
>
>Yes, I have seen that as well. However, users are typing it.

How about introducing the formatting buttons? There's lots of free code doing that in various forum platforms. Then the actual markup may be just a span tag with a class of your own. There's room for that in the bottom right line of the message header, below message ID. Just the minimal set of tags - bold, italic, strikethrough - what people already use. So at least we wouldn't be seeing people trying to "use" quotation "marks" for "emphasis" :).