Let's keep in touch by e-mail.

Computers are used to send messages by e-mail.

Did you receive my e-mail of January 10?

I wonder if you received my e-mail on January 10, since I have not heard anything from you yet.

Would you please send me details of your products via e-mail as an attachment?

If there is already an account, there is a system by which you are able to send and receive email.