The mailbox may have some emails with an excessively long subject line that are not supported by Windows Phone 8. Once you have removed the suspect mail item (i.e. cleaned the mailbox or move the suspect mail to a folder that phone does not sync) the error will cease.
- Can I get a notification if I receive call or text messages from blocked numbers?
- Can I transfer the messages and contacts to a file on my Lumia phone?
- How can I block phone calls and text messages on my Lumia using the call+SMS filter app?
- What can I do if the screen on my Lumia will no longer rotate?
- I cannot send or receive text messages on my Lumia phone