S3hit

I'm now down with the kids (and as of today totally out of date) and have moved from my lovely Blackberry to a smartphone - the Samsung S3. I've just spent the entire evening trying to set up my 123-reg email on it, without success. I can't figure out whether the problem belongs to Samsung, T-Mobile or 123-reg. My work email I can set up fine. My virgin email I can set up fine. So I suspect the problem is 123-reg's but who knows why - certainly not their help page which is no use whatsoever? The outgoing pop3 setup works OK but I can't get the phone to access the SMTP server - it keeps rejecting my username and password, even though it works just fine for Pop3. Anyone? Halp?