Can't send emails when away from home

Question

I can send emails from my iphone when I'm at home, but not once I have left the house. I get the 'sending' bar at the bottom, but nothing ever happens. Any ideas?

Answer 1

When at home connected to your wireless network?
If so, is the email account provided by your internet service provider at home?
If yes, most internet service providers don't have an authenticated SMTP server with the email account they provide which is the problem.
Most, if not all ISPs block the use of SMTP servers that are outside of their network or not provided by the ISP unless the SMTP server is authenticated, and AT&T is no different in this regard when connected to the internet via their cellular network when sending email.
AT&T's SMTP server is included as an available SMTP server to select/use for an email account when connected to the internet via their cellular network if an email account does not have an authenticated SMTP server. This should work when connected to AT&T's cellular network but may not work when connected to your wi-fi network at home with your internet service provider being used for your internet connection.
I access two email accounts with the iPhone's Mail client. Both accounts have an authenticated SMTP server and I've never had any problems sending with either account regardless the internet service provider being used for my internet connection at the time.