I had that issue too, and just installed Geary which is enough for me - for now. I believe a future update will probably fix it if Evolution is still supported. I have been unable to find out if it's still supported, believe it or not, since all mention of it on Gnome.org is a couple of years old. It's not a GhostBSD issue, but one probably related to an old application using a dependency (GTK4) that it can't really handle.