There are well-known reputable organizations in the U.S. that spam me because someone else entered in my email address and those organizations never validated the email address.

I mark them as spam, but it takes a long time for them to start going to the spam folder instead of the inbox.

I'm sure there are users here that are employees of these organizations/companies/etc. Please make sure your organization is validating emails! 'Never trust the user' should extend to email addresses too.