NoSparks,. . . YOU Are BRILLIANT ! I Love you !
I just downloaded your spreadsheet, and It Works ! I don't know How it works, But It Does !
I've seen a few other VBA solutions that allegedly might work, but:
I can't even install the durn things; can't even get them to do anything.
And That Right There Pisses Me Off ! Never done any VBA stuff before, but
I ain't no dummie; been Working with computers for 45 years.
Back then, I was programming Assembler language on IBM mainframes.

Searched for "how to install an excel vba script" and read all of:
How to Install and Uninstall A VBA Add-in File For Microsoft Office — The Spreadsheet Guru
How To Use The VBA Editor In Excel: Explained Step-By-Step
How Do I Create a Microsoft Excel Script? | It Still Works
Insert and run VBA macros in Excel 2016, 2013 - step-by-step guide
How to Create Visual Basic for Applications (VBA) in Excel with Examples
How to Create a MS Excel Script | Chron.com
Still, cannot make a FUNCTION or SUB script do anything.
I even tried getting MrExcelHTMLMaker do do something; no success.
So as not to waste too much of your time,
can you point me toward some further reading to learn how / why this thing now Runs?

You mentioned a StackOverflow thing to make Tbird auto-send the email. I don't want that.
I only want the outgoing email to open up, and your VBA thing does exactly that.
I will need to edit the email before hitting Send.

I'm going thru your spreadsheet, to try to determine HOW the VBA thing runs.
In Excel > Developer > Visual Basic, there are 8 items under Modules.
Of course, zzChangeLog is not really neccesary, but I'll leave it there.
And zAntiquatedCode is also probably not used?
mUI is empty. Why is it there?

I assume that the main control part is in Sheet1 (test255), also called Sheet1 (Code).
I see where the TO and SUBJECT and BODY come from, but how does the operable Link get into column A?
I don't see how column A cells are filled.
That info is needed because in my real spreadsheet, the operable links are in column F.

Tried to make a minor change (changing "Click here" to "Click"), but the spreadsheet didn't change.
Even saved the file (as a different name), exited Excel, then re-opened the file.
I searched; that "Click here" text now appears nowhere in all 12 modules,
but the spreadsheet still says "Click here". Why is that?
Crap. FergetAboutIt. I simply changed the text IN the Spreadsheet. That worked.

In that same module, you referenced the TO cells with Set rng = .Range("B10:B30")
My real spreadsheet will have anywhere from 50 to 150 rows.
Can I set that to Set rng = .Range("B2:B200") even though cells B190 to B200 will probably always be empty?

Crap. Just to test, I changed that to Set rng = .Range("B10:B20") and cell A28 STILL WORKS.
OK. I apparently don't know how to change any of the parts in the VBA script.

Now, I need to learn how to adapt your VBA thing to my real spreadsheet.

THANKS VERY MUCH. I clicked to Add to your reputation.