Are these internal (i.e. from another Gmail user) or from another external system? I've never seen an internal (i.e. OOO from a colleague in the same organisati

Are these internal (i.e. from another Gmail user) or from another external system? I've never seen an internal (i.e. OOO from a colleague in the same organisation) marked as spam. I assume some email systems will treat their own OOO emails differently--and in fact I am pretty sure this is the case for Exchange for example. But I can see how it could happen for OOO emails from another system which would be handled simply as any other email. My money would be on Gmail marking the email as spam. I don't recall Mac Mail doing any special spam filtering.