Change e-mail notifications to only be sent when recipient is offline (#17984)

* Change e-mail notifications to only be sent when recipient is offline

Change the default for follow and mention notifications back on

* Add preference to always send e-mail notifications

* Change wording

config/settings.yml

@@ -38,16 +38,17 @@ defaults: &defaults
   trendable_by_default: false
   crop_images: true
   notification_emails:
-    follow: false
+    follow: true
     reblog: false
     favourite: false
-    mention: false
+    mention: true
     follow_request: true
     digest: true
     report: true
     pending_account: true
     trending_tag: true
     appeal: true
+  always_send_emails: false
   interactions:
     must_be_follower: false
     must_be_following: false