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.
- How do I check if there are new updates available for my Lumia phone?
- What if I have trouble installing an update on my Lumia phone?
- My Lumia stays at the spinning gears, how do I get it to stop?
- Does my Nokia Lumia use an IP address when it accesses data networks?
- Can I use my Nokia Lumia as a tethered modem for my laptop?