Click and drag the email into the Primary tab. Click Yes to confirm.
Apple Mail: Right-click on the sender's email address. Select Add to Contacts or Add to VIPs.
Iphone/Ipad: Open the email, tap senders name in the from line. On the next screen, tap Create New Contact. Click done.
Tap to open the email. Tap the icon next to the email address. Tap OK.
Right click the email. Hover over Junk, then click Never Block Sender.
Web version: Click the gear icon. Click Junk Email Options. Select Safe Senders Tab and click Add. Enter the email address you want to safelist.
Right click the email. Select Add Sender to Contacts. Click Save.
A simple way to keep an email out of overzealous spam folders is to add them to your address book.
You can google "whitelisting" for your email provider for instructions.
If you're still having problems with missing emails, check the settings for any security apps like Norton or McAfee.