
SOLUTION (for Catalina & Mojave users) is, use THUNDERBIRD.

Simple & trustworthy, and more uptodate, and more devs supported, and more user supported, etc based TB (since v?) has began to include GPG 1 tool, and from TB v78 (for Windows/Linux/Unix, & different version ? on macOS) it transitioned to use builtin OpenPGP 1, 2, 3, so separate GPG/PGP tool not needed anymore), so user/you can send+receive digitally signed and/or encrypted emails with it, for free. Thunderbird 1, 2 (TB) is a better alternative choice for some of those missing options. (See detail instruction & goto bottom side for more info, if you have time)ĮXTRA INFO, PLEASE SKIP READING BELOW, IF YOU DON'T HAVE TIME :Īpple has removed many other supports from many other Apple apps, and if you were depended on those, then
YAKYAK FOR CHROME MAC
Another option is to use a HyperVisor 1 (aka: Virtualization 1) app (f.e.: VirtualBox) to run another/second instance of a macOS (f.e.: High-Sierra as a guest macOS), inside a guest virtual Mac computer/machine in the host macOS Mojave/Catalina/BigSur, and use the "Messages.app" with GH network support/feature & other apps inside guest macOS, as specific feature necessary for user is missing(aka: not-present) in host macOS.(See detail instruction shown below for more info, if you have time)


But user "JBis" has shown at-least some partial way to copy specific files, settings, etc from older macOS to Mojave/Catalina.Google-Hangouts (aka: GH, aka: classic Hangouts, previously aka: Google-Talk, aka: GT) support was dropped from Mojave & Catalina, so "Messages" app cannot use that web-service (aka: network) anymore normally, and a complete solution is not-found yet.
