It depends on whether you think "ungrammatical" means "not approved of by prescriptivists", or you mean "not used and/or not understood by fluent speakers". Gi

It depends on whether you think "ungrammatical" means "not approved of by prescriptivists", or you mean "not used and/or not understood by fluent speakers". Given that you know the word "pro-drop", I assume you know this, and I'm not sure if I should bother continuing in this vein. Maybe you're asking for a descriptive grammaticality judgement from fluent English speakers? I agree that from a prescriptivist perspective, this is improper formal writing. From a descriptivist perspective, I try to avoid biz guys, but I suspect the GP post nailed it, with respect to common usage in the appropriate sociolect (the same sociolect that has "proof points", "value-add", "circling back", etc). Although maybe not for the last sentence of an email that already had that much circumlocution.