That's not good! I know unknown error messages can definitely be cause for alarm. I want to help. It sounds like your settings for the email account require a copy of the message to be left on the server. Please remove this feature from your email client, this will allow the message to be deleted from the server when you delete them from the phone http://support.apple.com/kb/HT3228. You can also check in the email client settings to see if there is a way to increase your mailbox size. This would get rid of the mailbox is full error message that you are receiving. Have a great day!
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