How to block all email from a country code or other Top Level Domain (TLD)
Resolution
Method 1
Add the TLD to the Local Bad Sender Domains. (Reputation -> Bad Senders -> Local Bad Sender Domains) Use the format *.tld (with the * being a wildcard)
Example: *.ca *.website
Method 2
You can create a content filtering rule that will allow you more flexibility. It will allow you to create exceptions to the rule or specify a policy group for the rule to apply.
Create a dictionary (Content -> Dictionaries -> Add)
Name the dictionary (i.e. Blocked TLD's)
Enter a TLD and click Add (Repeat as needed.) Click Save when finished.
Click Content on the top menu bar.
Click Add to create a new content rule.
Click select to start with a blank rule.
Name the policy (i.e. Block TLD's)
Under Conditions, change apply to to inbound messages.
Under Conditions, click Add.
Select "Text in the specific part of the message header" and select Envelope Sender in the drop-down to the right. Change "Email address" to "Country code". Select the dictionary you created in step 1. (i.e. Blocked TLD's) Click Add Condition.
Configure an action under Actions.
Select groups to apply the rule to under "Apply to the following policy groups" Click Save.