We already can block authentication to the server by country.  I propose a similar feature for inbound SMTP connections, to block based on originating country.  Yes, I know geolocation databases can and do have errors, but generally speaking they would be good enough for many regions of the world we'd like to block.  Give us the same options as with authentication filtering-- let us choose to "block these" or "block all except".  Both options are useful depending on circumstance.

Currently, we use HE's BGP looking glass to view source IPs that hit our honeypot mailboxes and base our blocking decisions on the provider that holds those blocks AND/OR the country of origin.  We've found the vast majority of our Spam/Scam/Phish captures come from a relatively short list of countries.  And we know Smartermail already has geo-lookup capability built in, because when we Blacklist a network, the Country field auto-populates.

PLEASE UP-VOTE if you agree.