If you have a Gmail account, you need to be checking your Spam folder every day or so.  

All email systems have a spam or junk folder, where they temporarily park suspected spam messages before permanently deleting them. 
However, unlike most other email systems, Gmail normally hides the spam folder. 

It is easy to make your Gmail spam folder visible:

Go to https://mail.google.com/mail/u/0/#settings/labels

Find "Spam" in the list and click "show" 

(If you are not using some of the other labels -- like "Snoozed" or "Chats" -- change them to "hide" to reduce the clutter.)

--cg