Gmail
Mark messages as ‘Not spam’
If Gmail has marked emails you wish to whitelist as spam, tell Gmail the emails from @real.intercom-mail.com and @joinreal.com are not spam.
In Gmail, navigate to the spam folder.
Search for emails from REAL
Select all the emails shown.
Click More and then Not spam.
Create a filter for the address
Create a filter to tell Google to whitelist email from REAL
Click the cog icon in the top-right corner, and then Settings
Click on Filters and then Create a new filter
Either enter the domains of REAL (@real.intercom-mail.com and @joinreal.com) in the From field or enter the email address you want to whitelist in the To field
Click Create filter with this search
In the box headed When a message arrives that matches this search select Never send it to spam
Click the Create filter button
Outlook
Select Settings > View all Outlook settings.
Select Mail, and then select Junk email.

3. If you see the REAL's address (@real.intercom-mail.com or @joinreal.com) listed under Blocked senders and domains, select that address and then select Remove > Save.
If the sender's address isn't in your Blocked senders list, you can add them to Safe senders and domains. Email from contacts in your safe senders list will never go to the Junk Email folder.
Select Settings > View all Outlook settings.
Select Mail, and then select Junk email.

3. Enter the sender's email address, and then select Add > Save.
For more information please click the button below.
Outlook.com (formerly Hotmail)
Open your Outlook mailbox.
Select Options from the top right (next to the question mark).
Select More options > Safe and blocked senders (under Preventing junk email) > Safe senders.
In the space provided, enter the address. Example: You can either enter a specific email address or use @joinreal.com or @real.intercom-mail.com to whitelist the domain
Select Add to list.
Ensure the safe mailing lists box has the address you entered, and select OK.
Yahoo
First, find messages from REAL (sent from @real.intercom-mail.com or @joinreal.com) and mark them as not spam.
Click on the Spam folder.
Select the email.
Click Not Spam at the top of the page. The email will return to your Inbox.
In Yahoo Mail, your contacts list is your whitelist. To add the From Address to your Yahoo Contacts:
Open your Yahoo mailbox.
Click the address book icon under the Yahoo! Mail logo. When you roll your mouse over it, it will say Contacts.
Click "New Contact".
Fill in the fields of your Contact.
Click Save.
AOL
First, find messages from REAL and then mark them as Not Spam
Open your mailbox
In the left panel, click Spam
If you find the email from Real (sent from @real.intercom-mail.com or @joinreal.com), click the box next to it, and then above your messages, click NOT SPAM
Next, add Real email addressed to your contacts list to ensure that mail is delivered to your Inbox
Open an email from Real
Click on the sender's name and email address
Click "Add to Address Book" in the window that appears
Enter any additional information
Click Save