With the rise of the global spam problem, service providers such as Gmail, Yahoo, and Outlook have improved their spam filters to try to keep up. The problem with this is that legitimate emails sometimes get caught up in these filters and end up in the spam box. The best way to ensure you get to see the emails you want is to whitelist them. This protects them from overzealous spam filters and ensures the right emails hit your inbox and not your spam folder.
What is email whitelisting?
Whitelist is the process of adding an email to an approved sender list, so that emails from that sender are never moved to the spam folder. When an email address is whitelisted, it tells an email server (like Gmail the recipient) that they know and trust the sender and should move messages to the inbox directly. This helps to avoid important emails being sent into the spam folder because the service provider does not find a particular email in its database of valid IDs or when you have not added it to your contact list.