Email or e-mail (/i:meɪl/) is a communications medium with which you are familiar.
Emails follow certain genre conventions, with some variation between personal emails, business emails, spam emails, etc.
Note having students write "emails" in class on paper with a pen, is hardly replicating real-world conditions, and the authenticity of the task might be compromised. In real life, email authors have access to dictionaries, Google Translate, etc. But they may also be working under pressure.