sender address rejected by server
New iPad2 - Set up Mail with settings for third party POP account. The account already works fine on an iMac, Macbook Air and iPhone 4. However while it will receive mail it wont send - message is 'the sender address ..... was rejected by the server'. I have entered the settings several times and rebooted. I set up a Mobile Me IMAP account which works fine receiving and sending. Any ideas? Got to be a simple fix...
iPad 2, iOS 4.3.1, Mail error