Currently Being ModeratedMay 3, 2012 2:14 PM (in response to Michael Black)
Thank you Michael,
My real problem was that for some reason my iphone had changed the default (probably me but didn't know I had done it), but also everytime I used e-mail on my Iphone - my desk top computer's email system crashed.!!
But only my iphone affected it. Other people's Iphones email messages did not.
I ended up deleting my email address from my Iphone - entering it again as a new one! and then using your answer to make it the default
All OK so far