Iphone 4 - I can receive email but cannot send

Hi!
When mail being sent from iPhone, it will be used the outgoing email server you had setup for the account sending email.

If it works on wifi and not by carrier, it means most likely one of the following:
a: carrier blocking SMTP using any other mail server than the carrier's one
b: your outgoing email server not reachable from external network (an example: 192.168.x.x server, it is a local subnet server, will never be reached from outside)

You can ask your carrier what is the outgoing email server you have to use, and add it to the "other smtp servers" info of your email account. When sending email, iPhone will try servers listed there if main will fail on send.

Having the same issue since I upgraded to iOS 4.3.

Can't send email through my GoDaddy server (smtpout.secureserver.net) if I'm not on WIFI. Carrier is Fido, in Canada as well.

Not sure who's the culprit here. Apple (since it's really a problem that occured since iOS 4.3) or Fido....?

I had the problem for almost a year now and i found out that fido blocked it.

Pretty simple, instead of using smtpout.secureserver.net as your smtp server, use gprs.fido.ca with port 25.
no SSL, no username, no password.

It finally worked for me!! 🙂