All Domain Impersonation Protection, not just freemail domains
There is VIP impersonation in Sophos Email now. however the feature is limited to "just" freemail providers. I opened a case regarding this to find out why phishing attempts with our CEO name were coming through, and its due to the fact they were using an icloud.com address and not a gmail.com address! The feature is too narrowly focused to be useful as most impersonation attempts come from custom domains, not freemail services.
The impersonation protection is just a warning anyway, so we should be able to blanket cover all domains that are external to us with a matching VIP name.