Using classic Outlook for Windows in business environments
^ THIS
Be advised, if you aren't already aware, the spam/phishing emails that emanate from any other place than legitimate verifiable email addresses (which wouldn't be spam/phissing in the first place) will not actually unsubscribe you from getting more spam/phishing email, they are honey traps for you to keep giving the spammers/hackers more personal information.
It's this one man's opinion, they are garnering our email addresses and personal browsing preferences from web browser add ons/extensions which are either compromised or are purposefully selling our browsing data.
Email is broken all across the web from every major Email service provider, and it's only gotten ordinates worse in the last 12 months. In order to stop this so far, the major email service providers would have to threaten each and every pop/imap/exchange exit server owner and isp, which up to this point they've been unwilling to do, because it would mean a great many tens of millions of innocent accounts, providers, isp's would be caught up in the crackdown, breaking the internet
Thanks for coming to my TED talk.
They have no solutions, no solution is coming, save yourselves, trust no email.