Fix – The Message Could Not be Moved to the Mailbox Trash iPhone
Here’s how I fix The message could not be moved to the mailbox Trash:
1. Go to Settings -> Mail, Contacts, Calendars
2. Select the account that is giving you the message, Under IMAP re select the account.
2. Select Advanced -> Deleted Mailbox option and manually select the Trash folder on your account. Solved!