Q: I am unable to send e-mail messages from my iPhone5.

Hello scopenn,

To get to the settings of your email on your iPhone, go to Settings > Mail, Contacts, Calendars and then tap on the effected email and you should get you to a starting place to look at the settings. You can also delete the account and then add it back in to get it working again if you are stuck. Take a look at the article below for more information. 

Get help with Mail on iPhone, iPad, and iPod touch

https://support.apple.com/en-us/TS3899

Regards,

-Norm G.