Hello again, Mike:
Were you able to use any associated Google mail derivatives & seek missing content across their archives?
AirMail essentially is surrogate to gmail. Anything it may do, Gmail can do; perhaps better once tweaked.
For most anything in Mac's storage; those two-linked applications in my first reply, could be very useful.
Easy Find, free; and Find Any File, a shareware that runs free. ~ Both these I have & use; their usage is
a matter to learning their curve. Expect them 'fair to excellent' & depends on any lessons you learned.
Perhaps a 'boolean search' may be a chance-search operative to explore
while not necessarily helpful in confines of your Mac's storage drives.
(To access your email through Gmail web login can provide more info.)
"Airmail .. plays well with other services, supporting document import
from OneDrive, Google Drive or Dropbox and letting you open links in
many different browsers; it also features “send to” support for apps and
services such as Trello, Evernote, and Pocket" (AirMail ref. similar macOS)
~ from Tom's Guide, best apps Jan. 2021(iOS).
Anyway, hopefully a different scheme of email archive will result.
Adaptive? One both serves immediate, & future use; of course.
