What is an email whitelist?
To whitelist an email address just refers to the process of adding them to your approved senders list. Whitelisting tells your email client that you know this sender and trust them, which will keep emails from the sender out of the junk folder.
How to whitelist an email address
Outlook
Access the link: “I trust sender@theirdomain.com. Always show content.”
Gmail
Getting all future emails from a sender to appear in the “Primary” tab is a quick, two-step process.
Yahoo! Mail
Select the “+” symbol next to the sender’s name and use the link to “add to contacts”.
Apple mail
Select 'From', or Reply-to on an email message, you can choose to “Add to Contacts” or “Add to VIPs.”
Android
Touch the picture of the sender that displays before the message. Tap “Add to Contacts.”
AOL mail
Select the sender’s 'From' name under the subject line and select “Add Contact”.