iCloud Mail continually goes offline
If the mail application is close, iCloud mail goes offline, although my other email accounts in the mail app do NOT go offline. When I open the mail app, there is a symbol next to the iCloud account (but not next to the others) that looks like a circle with a horizontal zig-zag. When I click on that symbol I get the following message: "This account (iCloud) appears to be offline due to a network problem." If I click the button in the dialogue box that says, "Take all accounts online,", then my iCloud mail comes in right away. However, all my other mail accounts already are delivered. It is not a network or connection problem. My iPhone and iPad also do NOT have this problem. Any ideas?????
iMac (21.5-inch Mid 2011), Mac OS X (10.7.3)