I've been getting a couple of e-mails a day from various MAILER-DAEMON "Mail Delivery Systems"
Subject: Undelivered mail return to sender.
"This is the Postfix program at host rosalind.planitis.net" or some other such balderdash.
Then, I'm asked to download an attachment, "attachment21" Yeah, right.
Beneath, it shows a phony baloney returned email from me to someone I never heard of.
(Timestamp says I sent it midmorning, when I'm not home and the computer is turned completely off)
Then they ask you to download another attachment, "document_george.p.zip". NO
If you get these, delete them to your trash, and then manually dump the trash.