A draft e-mail .... when you need to make multiple revisions to a message before you send it. 

Any previously saved draft e-mails ... in the Drafts folder, similar to the image below.

In what gaps do we have Passive voice?

When an e-mail (1) send) to one or more recipients, you usually (2) assume the e-mail  successfully (3) receive by each of them. 

When an e-mail .... , you start to question what happened.

Complete the sentence:

Even if it ... (spelled) correctly, if the e-mail address does not exist, the e-mail cannot be delivered.

E-mails flagged as graymail often are ... to the Junk folder.

E-mails ... (send and receive) through a mail server. 

Similar to an electric typewriter, a keyboard ... buttons used to create letters, numbers, and symbols, and perform additional functions. 

When placing your hands on the keyboard, they ...  over the home row keys.

Clicking any of the keys .... (open) a new page with full details.