HT1430: Turn your iOS device off and on (restart) and resetLearn about Turn your iOS device off and on (restart) and reset
Currently Being ModeratedFeb 1, 2013 5:01 PM (in response to francisco1226)
Its either an issue with the smtp server settings or you have port 25 blocked on a firewall. Make sure you have no software running that could block internet traffic. Try deleting and re-adding your gmail account in mail.
EDIT: just noticed gmail uses SSL, so the port would be 465. Either way, turn off any internet protection software or similar and add the account again.