As far as I know there is no junk mail filter per. se. for either Mail or Airmail on any iOS device. However, since…
  • All of my emails accounts are IMAP
  • My desktop computer runs 24x7
  • I leave either Mail or Airmail open on my desktop 24x7
When junk mail comes it is detected by Mail or Airmail on my desktop and moved to the junk mail folder. When I check messages on either my iPhone or iPad the junk mail appears in the junk mail folder. There is a narrow, very narrow, window of time in which I may see the message in the Inbox on an iOS device before the Desktop checks mail and moves it to the junk folder — but as I say it is a very narrow window.

FWIW an advantage I have found with Airmail is how well it works with Spamsieve.

Last edited by joemikeb; 07/19/15 06:53 PM.
If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein