This huge (711 million records) leak would explain some email being sent from people's addresses and it contains email, password and SMTP server.
I commented on there - Troy's Have I been pwned service is great but it's getting harder now to manage passwords. If you have a website leak and know the source you know where to change the password but with leaks that are username + password then it's harder to know where to change. And since he (rightly) do not disclose the passwords in the dumps then those already using unique passwords have a harder time.
It seems we have to start using unique email + unique passwords to be able to better manage security. Those email aliases or emails with "+" in the address come handy here.
I recommend subscribing to the notification service at Have I been pwned so you receive notifications of leaks.