How to make sure important emails never get sent to spam
Email Address Whitelisting
Introduction
“Email Whitelisting” is a term used to describe the act of allowing an email to reach your inbox. This can be helpful if you want to make sure a sender doesn’t go to your Spam folder. These days, whitelisting is typically accomplished by adding the sender to your contact list in whatever email client you are using (there a few exceptions of course).
Step-by-Step Instructions
- Apple iPhone / iPad
- Open the email.
 - Tap the sender’s name in the From line.
 - On the next screen, tap Create New Contact.
 - Tap Done.
 
 - Microsoft Outlook 2013
- Right-click on the email that you would like to add to your safe sender list
 - Hover over Junk and then click the option Never Block Sender.
 
 - Android
- Tap to open the email.
 - Tap the icon next to the email address.
 - Tap OK.
 
 - Apple Mail
- Right-click on the sender’s email address.
 - Select Add to Contacts or Add to VIPs.
 
 - Gmail
- Click and drag the email into the Primary tab.
 - Click Yes to confirm
 
 - Outlook.com (formerly Hotmail)
- Open the email.
 - Click the Add to contacts link
 
 - Yahoo! Mail
- Right-click the email.
 - Select Add Sender to Contacts.
 - Click Save.
 
 
Source: https://help.infusionsoft.com/userguides/campaigns-and-broadcasts/email-deliverability-guide/email-address-whitelisting