Unfortunately many computer users don't think about privacy, or being cautious of what, were & who they email and contact or where they go online... they just don't have a clue sometimes

a friend /or a friend of theirs...could have got hacked.
Those fwd'd emails are a pesky thing..
A fwd from someone can get fwd to many others
without the original sender even knowing that their email address is getting to sent all over the place.

I have 5 email addresses and a couple of throw away ones for online newsletter sign ups or someplace that I don't want to use a main email address.

I never use my main Verizon email address. But did use the sub addresses set up and use the address guard feature.

And those "pass this on" things are the worst I think!
I delete those every time.
I wouldn't be surprised it they get started by spammers to collect email addresses!