I've had this problem on my iPhone for a couple of days now, thought it was probably a server issue that would be resolved but it doesn't seem to be going away. Basically, whenever I try to send mail using the Mail App I get this error message: Cannot Send Mail. The user name or password for "SMTP: firstname.lastname@example.org@smtp.live.com" is incorrect. I've had this phone for 7 months now and this is the first time I'm having this problem. I can receive emails perfectly fine, its just sending them that is giving me this error. I haven't changed my details at all and I know my PW and username are both correct. Someone please help. I don't want to restore my whole phone or anything like that if its avoidable.