As with Mail on OS X, the Mail app that Apple includes in iOS allows you to configure multiple e-mail accounts, but while you should be able to compose your e-mail and manage messages as you would in any e-mail client, there may be times when you run into an error when attempting to delete, archive, or otherwise manage your messages.

When this happens, you might perform an action like deleting the message, and while it will disappear temporarily, Mail will then show you a notice that states the message could not be moved, and it will then reappear in your mailbox. If you have multiple accounts configured in Mail, then this may happen for only one or two of them, so the error will only happen on messages in those accounts, as opposed to all the time.

If this problem is occurring for you, the easy fix is to re-assign the Trash, Junk, or other default mailboxes configured for the account in question:

1. Go to Settings > Mail, Contacts, Calendars
2. Select the problematic account
3. Go to Account > Advanced
4. Select your problematic mailbox in the Mailbox Behaviors list

For the selected mailbox, you should have a list of possible folders that your iPhone can use for storing the mailbox data type (ie, Trash, Sent items, Drafts, Archived items, etc.). Any of them should work, but you have essentially two options:

1. Chose On My iPhone, to store your Drafts, Trashed Items, or others on local mailbox folders
2. Choose a folder On The Server, to have your iPhone simply move these items to another folder on the server.

The second option is good for synchronizing with other e-mail clients, especially if you are using Exchange or IMAP protocols. By doing this, when you delete a message or save it as a draft, then it will be accessible from this folder from other e-mail clients. If you only use your iPhone for accessing this account, then the folder you select will not matter.

While these options are available, the true fix to this issue is simply to toggle the mailbox settings, so if you do not want to change your Mail’s default behavior, you can revert back to the prior setting. By simply doing this, you will spur Mail to overwrite its settings and reconfigure Mail to properly access the selected storage location.