It appears that the intended recipient, support@ourdomain.com, was simply not online at the time that the message got sent, or at least not online with the resource “android9km8yix6”. Think of ‘resource’ as an identifier for the client that a user is logged in with. XMPP users can log in with multiple clients at the same time, as long as each login specifies a different ‘resource’ value.
When this happens again, log into the Openfire admin console, and Open the “sessions” tab. By default, that page lists all client sessions. See if there’s a row where both the values in the column “Name” as well as “resource” match the ‘to’ JID. This is the syntax: name@yourdomain/resource
I would not be surprised if you only find a row for the ‘name’, but that has a different resource. If that’s the case, then the entity that sends the message is addressing the wrong recipient.