You have the spambots of the world to thank for that. The problem is that, like most ISPs, RoadRunner requires authentication in order to send email. This issue is that when you are home, using your own wifi, you are using your .rr internet connection, so your email authenticates quite nicely. But when you are out and about, you are using AT&T or VZW 3G services which cannot authenticate your .rr account because you are not connected to the .rr internet service.
Now, what to do about it...
I did find this info... understand that this was for an AT&T iPhone for a guy with RoadRunner service out of Texas... but since I don't have a .rr account, I cannot speak to the veracity of the "fix":
Link to source website
Mine works now. Here is what I have.
under my mail account:
on mail account - now i have the new ipone g3 (do not think it matters)
my email & password
Primary server firstname.lastname@example.org
authentication password (your rr email password you must have this input for outgoing too)
Use SSL on
primary server email@example.com
other server at&t smtp server ON
att server was already set @ cwms.com (i could not modify this area) other than on/off
Hope this works for you!
I am a happy camper! :-)