Icedove wants to delete messages that I've been archiving and placing in subfolders

Edit: Make that "purge" ... even more threatening than delete.

"What compact does not do

Compact (purge) is a maintenance process, so it:

does not delete messages from folders
does not remove messages from trash or spam folders
does not compress folders by using compression algorithms such as zip

You may be concerned that the compact prompt sometimes appears just when you have deleted a message, or when you have started Thunderbird. This is expected behavior and is not cause for concern, because compact does not delete your messages. "
https://support.mozilla.org/en-US/kb/compacting-folders

Looks like it's possible to turn off?
https://support.mozilla.org/en-US/questions/1225337

"Purge" in Icedove has an entirely different meaning than the same verb in Mate Terminal,
where there is a gradation from "uninstall" to "remove" to "slash; burn, collect the ashes
and send the ashes to outer space," i.e., "Purge."

"Compact folder[s]" was a term that I thought meant that empty disk space was to be retrieved
by placing emails in some order such as "head-to-tail" without gaps caused by previous moves
from one storage location to a subsidiary folder in another location. In a pre-computer
summer job I was instructed to do such a thing with randomly filed job orders in a four drawer
standalone file cabinet, which I proceeded to do in order of the date written, with the most
recent at the beginning (front) of each folder; took about a day.

In Icedove these settings are in an entirely different place:
Edit > Preferences, then scroll down to > Network & Disk Space, then scroll down to > Disk
Space, where you can uncheck "Compact all folders when it will save [ I entered 2 TB ]"

Wait ! There's more: at the lower right, below what you just saw, is > Config editor >
search the extremely long list that appears after you accept all risk > "purge" whereupon
the following list appears:
mail.prompt_purge_threshhold;false ... was true
mail.purge.ask;false ....................... was true
mail.purge.min_delay;480 ................... Is that minimum or minutes ?
mail.purge.timer_interval;5 ................ Seconds ? Minutes ? How many ?
mail.purge_threshhold_mb;2000000 ........... was 200 (I reset the threshold to an impossible level)
mail.purge_threshold_migrated;false ........ was true (ambiguous terminology)

There's more, equally ambiguous terminology:
mail.server.default.purgeSpam;false ......... My ISP is hypervigilant; often incorrect
mail.server.default.purgeSpamInterval;14 .......... Seconds ? Minutes ? Hours ? Days ?
privacy.purge_trackers.date_in_cookie_database;0 .. Days ? Day of week ? Calendar date ?
privacy.purge_trackers.enabled;false .............. Let the trackers do their thing ?
privacy.purge_trackers.logging.level;Error ........ Log the trackers when they fail to track ?
privacy.purge_trackers.max_purge_count;100 ........ Count from the latest or from the earliest ?

Continuing, then noticing the term, "bookmarks":
browser.bookmarks.max_backups;5 ............. Found fifteen, ca. 20kB each (I expected megabytes)
places.frecency.bookmarkVisitBonus;75 ...... Tribune spelling ? Ought to be "frequency." Relic of DOS ?
places.frecency.unvisitedBookmarkBonus;140 ... "Bonus" has the connotation of a commercial term.
Do these ambiguous terms affect Abrowser's practice of making my bookmarks impossible to retrieve ?