The discussion above is specifically about Yahoo's
push mail which is different from every other mail service's.
There should be no trouble with the app's default "check mail every 15 minutes" and there is nothing special about Yahoo and notifications.
Now, there is this issue with Yahoo forcing OAUTH2 and blocking access to what they call "less secure apps", but that's something else entirely.
http://www.aqua-mail.com/?p=2986For any given account, it'll keep working until Yahoo turns off the "allow access to less secure apps" switch in that account, and then there is a way to revert this, and again allow access from AquaMail (and pretty much all other mail apps).