I'm helping a Spark customer set up xtra email their phone, but whatever I do I get an authentication error. I've tried 4 different apps, 3 different devices, including a Thunderbird client on a pc. All give authentication error. I even tried POP3, and still the same error. All port and SSL setting are exactly as they should be. Yet webmail access on any PC or Android tablet works fine. Online chat with Spark are adamant they don't ever block access. Could it be that they are anyway?