In Google:
- Simply mark the email you received from us as “Important” under the “More” dropdown
- Create a contact for the new email address
- Create a filter by clicking Settings>Filters>Create a new filter and enter the new domain above in the “From” field, click on Save search as a filter and select Never report as spam
In Outlook:
- Add the new domain to Safe senders list by clicking on the cog icon in the top-right corner and then More mail settings
- Add the new email to Safe mailing lists by clicking on the cog icon in the top-right corner and then More mail settings
In Yahoo:
- Create a contact for the new email address
- Create a filter by going to Settings>Filters>Add
For more instructions, visit https://www.lifewire.com/how-to-whitelist-email-addresses-4588603