How to fix the dreaded "Unable to Move Message" error in iOS Mail

Both Dennis and I have some new iOS devices (yay, iPad Pro!), and both of us experienced an annoying email error that would occur every time we tried moving a message from our AppleWorld.Today email inbox to the Archive or Trash folders. The error message said "Unable to Move Message - The message could not be moved to the mailbox Archive." 

The fix ended up being quite simple, and it can be useful in a number of similar situations. What causes this is that the IMAP Path Prefix hasn't been set up properly. This can happen with IMAP accounts that require that the Path Prefix be set to INBOX, and that was the case with our AppleWorld.Today email accounts. To fix it:

  • Go to Settings > Mail, Contacts, Calendars
  • Tap on the account that is having the issue. You'll see a screen similar to the one seen below
  • Tap on the Account line with your email address listed 
  • On the bottom of the Account information screen that appears, you'll see an "Advanced" button. Tap on it
  • On the "Advanced" screen that appears, swipe down until you see Incoming Settings, then tap the line that says "IMAP Path Prefix". By default, this will be filled with a forward slash ( / ). Type the word INBOX in all caps. 
  • Now tap Account at the top of the screen to get back to the Account display, then tap the Done button in the upper right corner of the screen to save your changes.

You should not see that error message again... unless, of course, you set up that same IMAP account on another new iOS device in the future. At least you'll know how to fix it this time!