The best way to make sure the emails you really want to receive don’t get sent to spam is to whitelist the addresses from the people and companies you know. To ensure your important emails are delivered to your inbox, you can add our email address to your inboxes whitelist, also known as Approved or Safe Sender list.
How to whitelist in Gmail
To make sure Gmail never filters our email as spam, all you have to do is mark the conversation as important and add us to your contacts list. Gmail may mistakenly send a message from us to your spam box. If this happens, open your spam box and the message from us. At the top of the email there should be a button that says “Not Spam.” Clicking that will make sure you continue to get our messages in the inbox.
If that doesn't work, you can try the following:
How to whitelist in Outlook 2019
How to whitelist in Apple Mail
How to whitelist in Aol Mail
How to whitelist in Yahoo Mail
How to whitelist in Microsoft
Steps apply to Outlook.com, Hotmail, Live, or MSN