Please make sure to complete following steps at the end of contract or cancelation of Email Security.cloud
Caution: As long as your domain(s) remains on Email Security.cloud, emails from other Security.cloud customers that are provisioned on the same clusters will be sent using internal routing and not the MX records configured for the domain. This can lead to issues with mail delivery if your configured inbound routes are invalid or if a valid recipient email address has not been updated on the Address Registration setting. Therefore, please consider removing your domain(s) immediately at the end of contract or cancelation date.
To begin, change your MX record away from Symantec before canceling your service. See Change your MX record away from Symantec.
When Symantec Email Security.cloud intercepts an infected email, the service stores the email in quarantine rather than delivering it to the intended recipients. Before you remove your domain(s), you can release email from quarantine so that the email is delivered to the recipient.
Caution: You cannot release email from quarantine once your domain(s) has been removed from Email Security.cloud.
For more information, see Release email quarantined by Email Security.cloud.
When your domain(s) is removed, Inbound/Outbound Routes, Address registration are removed automatically.
Caution: All reports and logs will be deleted once your domain(s) has been removed from Email Security.cloud.
For more information, see How to delete a domain in Email.Security Cloud portal.