I have deleted my account several times and rebooted my phone I have done a restart and a hard start and I am still having issues. My account is a Yahoo account that always worked well with the android email feature now it does not want to work.
Having the same issue with YMail using the standard email client. Worked fine until yesterday. Gingerbread update 18 hrs prior to issues starting. Also did maintenance update about 10 hrs prior to problem starting. Last email received was at 12:33pm yesterday.
Updated to Gingerbread when it first launched, didn't do the maintenance update yet, my yahoo mail stopped working sometime after 10am yesterday... Same with my GF's EVO, except her also says her password is incorrect.