If your gsuite is not able to receive emails from a particular domain , it can be owing to many reason , the most commonly occuring issue is the domain blacklist case
How to whitelist your domain
- Login to admin.google.com with your superadmin login
- Scroll down to bottom
- Click on more settings
- Select domains
- Select whitelist domains
- Enter your domains one at a time
- Save and exit
Note whitelisting a domain can take up to 48 hours , be patient and try sending mails in 48 hours
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