Taking advantage of large PC/MAC keyboard to type your email into a text file, myEmail.txt on PC or myEmail.rtf on MAC, drag it and attachments (if any) into iTunes, a new email will pop up on iPhone with all the files in attachments and myEmail.xxx as email body. Choose your addressee then press send on iPhone.
Work with your iPhone connected to your PC/MAC via USB cable, nothing else is required. No need for WIFI or tethering. Especially useful when you PC/MAC cannot connect to Internet and your iPhone is not allowed tethering. The data is exchanged between your computer and your iPhone via the USB cable, therefore the iPhone must be connected to the computer with the USB before you can see the MAIL file sharing appear in your iTunes and before you can drag files into the MAIL file sharing window as shown in Screen shot.
PC: use notepad to write into myEmail.txt
MAC: use TextEdit to write into myEmail

SUPPORT: appli.help@hotmail.com (phone model, os version,problem description please).