IMAP Invalid credentials

IMAP Invalid credentials

I am getting an authentication error when attempting to connect via IMAP. I have confirmed my username and password are both correct. A screenshot of my settings is attached, and is set up as found in the article  https://www.zoho.com/mail/help/android-imap-access.html. I am using K-9 Mail on a Samsung Note II running Android 4.3, and have tested with the built-in mail client as well.

I've confirmed that the SMTP connection is working. This looks to be inbound only (both IMAP and POP, though I'm only interested in IMAP).