Spoofing: your own e-mail address shows up as the sender
Do not panic if you receive e-mails that appear to be coming from your own account. In principle, anyone can 'copy' or 'spoof' your e-mail address.
E-mail spoofing is sending mails from a fake e-mail address. This means that the actual sender, for example, copies your own e-mail address and uses it to deceive you.
How can I protect myself against e-mail spoofing?
Unfortunately, there is little you can do to protect yourself against e-mail spoofing. This should be done by your provider, the company that provides your mailbox. That's why you’ll often find such e-mails in your junk mail or unwanted mail, which means you know right away that you shouldn't trust these messages.