The best way to make sure that the emails you really want to see don't end up in the spam folder is to create a list of email addresses of people you know. While this is commonly called a safelist, the modern term is safelist.
How to Add Email Addresses to Gmail Safe Senders List
The procedure for adding emails to a safe list varies slightly by email service.
There is no quick checkbox in Gmail to add an email sender to an actual list of friends you want to keep out of the spam box. However, there are several effective ways to put your friends on a safe list in Gmail.
Open your contacts list in Gmail. The quickest way is to just go to the Google Contacts link.
