This resolution have to attend at the server not with the ios device. My employer's mail administrator reject me to correct it from the server. As his concern is, if ither ios devices works why don't mine? So I am helpless than changing my iphone. It works fine for early versions of ios and with androids. And also one of my friends iphone4 with ios 7 (similar as mine) works too. So I guess it's something wrong with my iPhones settings. But basic question I cannot understand is it works in my phone before this ios7 upgrading. And currently working with my yahoo account too. Favourable reply expected.