After several unsuccessful attempts I finally figured out how to get my own multiline version of a tooltip below the IER button for update notifications (and only for these, the default ones will keep the aspect of Pegasus Mail's default as shown farther below) to provide some more instructions on what to do next, here it is in Win 7 design (on Win 10 certainly looking a little cleaner):
I also took the chance to directly open IER's history & download page from the menu instead of bringing up even more possibly annoying dialogs before the download can be triggered. You may try it by testing the older version if you've already installed the previous one and try to use the update notification for downloading this one.
To make testing complete I'm also providing a link to the first "repository" version even though it doesn't completely match the criteria to be really significant - just for testing.
IER's "homepage": < https://www.pmpgp.de/renderer/History.htm >
Download URL: < https://www.pmpgp.de/renderer/IERenderer.zip >.
Michael -- IERenderer's Homepage PGP Key ID (RSA 2048): 0xC45D831B S/MIME Fingerprint: 94C6B471 0C623088 A5B27701 742B8666 3B7E657C