>>> Suggestion 1: Change the background colour

I also agree that, at the very-very least, changing the NM badge to some warning shade (red/maroon with yellow letters?) would visually help to alert the mod, if nothing else it could have prevented me from going into a rabbit hole trying to troubleshoot a similar NM issue a few days ago! lol 

The other reason I'm also supporting this is in the PS text, it diverges slightly so I put it there.

>>> Suggestion 2

I can see value in somehow marking/tagging/whatnot a group message depending on group function/purpose and settings, especially on research especially, news/opinion, (civil) political discussion, proposal, etc., any group function/purpose which you would want to visually identify posts coming from non-members (or non-experts?) for any reason.

The admins can always find out about that message/member if needed through the log, so at least that's covered. 

Regarding archive visual indication solution, regardless, logic would also have to be implement that happens right after member approval, to somehow retro mark/tag/whatever any already-posted nonmember-marked messages by that user before they were approved, only applicable to the UI of course, we wouldn't want to send out another same email message.  Depending on what's agreed, it may necessitate having a new status/badge/etc, XNM, "Ex Non-Member" (grey background light grey letters?), I don't know, but if we don't do some check like this, we would end up with the paradox of a (newly-approved) group member seeing their own messages online marked as having come from a [currently] non-member. :)

A XNM/whatever badge could also potentially be of use on groups which value membership status or message source in considering/weighing/rewarding content contribution.

Cheers,
Christos

PS: As a matter of fact, I would argue that we should take this and apply it further to the rest of the user badges, set special colors for them, or at least the most important ones; research has shown that old-school round steam gauges have one superiority to digital readout displays because, after you have familiarized yourself with the gauge layout and settings/values/"badges", it only takes a quick glance (or peripheral vision) to know where the dial is hence what setting/value/"badge" it points to, you don't have to "read" the instrument, or oven look directly at it; but you have to literally look and read the digital number display.  Anyone here who flies will attest to that, PPL to ATP, doesn't matter.  For the non-pilot folks, a quick test comparison between an old school round clock and your microwave's clock will show you that effect; and if you keep the clock within your nearer peripheral vision field, like let's say right next to your monitor, you can be looking a the monitor typing or whatnot, and still get a very good idea of the time without looking at the clock.  You can't do that with a digital number clock, you have to look at it and read it.

Similarly, right now in the sea of light blue, reading is your only lifejacket; but with different badge colors, after we memorize them, a quick glimpse/glance can warns us, plus tell us what's going on; one side benefit would be that if one had the whole member list onscreen, a scrolling sweep or two would give you a good idea of the [badge/user setting] group distribution, kinda of a visual self-reporting tool. 

Maybe I should start a new topic and reference this one.