Never open it even if it comes from a known sender.

Never open it even if it comes from a known sender.

Never open it even if it comes from a known sender.

It should never be opened even if it comes from a known sender.

It should never be opened even if it comes from a known sender.

It should never be opened even if it comes from a known sender.

Never open it even if it comes from a known sender.

Do not open ANY attachments that are not from a known and reliable source.

(There are lots of ways this is done, not all of them obvious, but which require a known sender).

You should only download an attachment from an email if you know the sender and are certain that his/her account has not been compromised.

Spoofing is a tactic used by spammers to make it appear that the message is from you in order to trick the recipient into opening it.

We wouldn’t be surprised if known names such as Amazon or eBay were used because users would drop their guard when dealing with a known sender.

A valid digital signature gives a recipient reason to believe that the message was created by a known sender, such that the sender cannot deny having sent the message.

A valid digital signature gives the recipient reason to believe that the document was created by a known sender and that the sender cannot deny having created the document.

To spoof a website or an email address means faking the identity of another user or company to make it look like it's from a legitimate source or a known sender.