To whitelist an email address means that you add them to your approved sender's list. This tells your email provider that you know and trust the sender, which will keep emails at the top of your inbox and out of the junk folder.
Apple Mail (OS X and iOS devices)
Apple makes it delightfully easy to whitelist emails. Simply select the From or Reply-to on an email. From there, you can choose Create New Contact or Add to VIP.
Caution: If you choose Add to VIP, your emails will show up in a special VIP mailbox.
Android (Default Email Client)
Android’s process is similar to Apple’s. Just open the email message and tap the picture of the email sender that shows up before the message. Then, tap Save contact to my device.
Start by finding an email from a sender you want to whitelist and add that sender to your contact list. Next, create a custom filter by clicking on the gear icon and selecting Settings. Choose Filters and Blocked Addresses from the menu at the top of the page and click on Create a New Filter. Enter the email address you want to whitelist in the From field and click Create Filter. Now, check either Never Send It to Spam or Always Mark It as Important and click Create Filter.
In Gmail - moving Senders From Social or Promotions to Primary
If you get an email in your Social or Promotions tabs and you’d rather those emails come to the Primary tab instead, you can make that change in a couple of steps. Start by dragging and dropping the email message from the tab where it currently is to the Primary tab. After you’ve done that, you should get a message that asks if you want to do this for all future messages from that sender. Choose Yes.
Outlook 20XX and Outlook 365
Choose a message from the sender and choose Home > Junk > Never Block Sender
Windows Live Desktop
When opening an email in Windows Live Desktop, you’ll get an alert that says Some images in this message are not shown. Choose Add to Safe Senders list.
When you open an email in Yahoo! Mail, a plus symbol will appear next to the From information. Click the symbol and you’ll see an Add to contacts popup. Choose Save.
Choose an email from the sender you want to whitelist, click the sender’s name and choose Add Contact from the dropdown.
Open your email. Click Options > Block Senders > Safe List and enter the sender’s domain. Then, click OK.
Choose Options > Filters > Add Filter. Choose contains from the dropdown menu and enter the email address you want to whitelist. At the bottom of the screen, you’ll find an option that says Move the message to and choose inbox from the dropdown menu then choose the Add Filter button again.
Go into your Address Book and click New > New Contact. Enter the email address then click Save.
Open up your email and click Preferences > General Email Preferences > Blocked Senders. Add the email address you want to whitelist in the Exceptions List then click Add and then Save.
Find an email from the sender you want to whitelist. If it’s in your Junk folder, just right-click on the email and choose Mark As Not Junk. Open your address book and make sure your Personal Address Book is selected. Click New Card and under the Contact tab, add the email to the email dialog box and click OK.
Open the email and click the plus symbol on the sender’s email address. Add a first and last name and then click OK.