We're now using MCGuardDog to help filter the tremendous volume of spam we've been getting, but some of the spammers are still using the old DNS MX entries to bypass that service and there's no telling whether they'll ever stop using the original MX entries. I'd love it if I could restrict all incoming email to coming from MXGuardDog and reject all email that's coming in directly to Zoho.
Of course it would be preferable to not have to filter like this, but honestly Zoho's ability to block (not accept and route to a spam folder) is pretty rudimentary and not having an option to reject incoming mail based on a block list, a TLD or IP ranges pretty much requires that we do this.
Thanks!