You can use a sent or received email to create a new email to send again.

When viewing an email, tap on the action menu button (circle with 3 dots) and choose "Resend". This will create a new email from the previous email. All of the formatting and attachments will be kept the same. You can also select an email in the folder list view and choose "Resend" from the action menu there too.

Your own email address will be used as the "From" address. If you have the "from" address in your outgoing account settings or an email alias, then the From address will remain the same.