Documents may be delivered to the association only by the following methods: (i) First-class mail, postage prepaid; (ii) Registered or certified mail; (iii) Express mail; (iv) Overnight delivery by an express service carrier; (v) Electronically (email, facsimile, or otherwise), if assented to by the association; and (vi) Personal delivery, if assented to by the association, with a written receipt. (Civ. Code §6512(b).)
All associations (commercial, industrial and/or residential) may decline to accept personal delivery of documents. But, in most cases, that would require a change to the governing documents, most of which expressly allow it.