First, I admit the notion of apostolicity outside the borders within which one puts the Church is a Catholic one. The Orthodox will go far as to admit ‘valid form’, etc. but are agnostic about grace outside Orthodoxy.
My use of ‘apostolic’ mirrors what appear to be Catholicism’s criteria for recognition of orders and Communion: basic credal orthodoxy (such as on the Trinity, divinity of Christ, hypostatic union, virgin birth and physical resurrection), a lineage of apostolic succession and — here’s the kicker — historically consistent, unbroken teaching and practice about the Eucharist (belief in the Real Presence — that the Sacrament IS the body, blood, soul and divinity of Christ).
Any church that has all these is seen unequivocally as apostolic — ‘valid’ orders and ‘valid’ Eucharist, in western Catholic-speak — by the Catholic Church. Such is how it views the Orthodox Church, the Oriental Churches, the Assyrian Church and small Western schisms that have maintained orthodox beliefs on these matters and have retained the form of the all-male apostolic ministry (the only such group in America is the small Polish National Catholic Church, descendents of an 1800s immigrant schism).
Such are Churches with a capital C from this POV.
The Orthodox, again, would concede that the forms are there in these churches but will add that the only guarantee of grace from their POV is to bring these forms into the community of the Orthodox Church.
There are also some Protestant churches that use the word apostolic in their names and as their denominational name but I don’t know what they mean by that. They don’t mean the same thing by it that we do here.