Sender receives a message in their mail logs of "Delivery temporarily suspended" when attempting to send to Email Security.Cloud servers.
Sending Server's IP is on recipient's Email Security.Cloud Blocked Senders list
The sending mail server IP may have been added to the recipient's Email Security.Cloud Blocked Senders list. Check to ensure the IP is not listed in the recipient's Email Security.Cloud AntiSpam Blocked Senders list:
Note: If you believe the Blocked IP was listed using CIDR notation, you may enter the last octet of the IP as wildcard using % instead. For example: IP 203.0.113.12 is receiving the error. In the Blocked Senders search box, you may enter 203.0.113.% to search for any IPs that would be covered under 203.0.113.0/24.