Due process requires proper notice.  Without notice, all may be for naught.  James Joyce's alter ego, Leopold Bloom, took note of this fact in the Cyclops chapter of Ulysses:

"Thank you, no, says Bloom.  As a matter of fact I just wanted to meet Martin Cunningham, don’t you see, about this insurance of poor Dignam’s.  Martin asked me to go to the house.  You see, he, Dignam, I mean, didn’t serve any notice of the assignment on the company at the time and nominally under the act the mortgagee can’t recover on the policy."

How service must be effected depends upon the jurisdiction and the type of person being served.  California's General Corporation Law provides that valid service of "any process" on a foreign corporation (as defined in Corporations Code Section 171) may be effected by hand delivery to:

• any officer of the corporation or its general manager in California, or if the corporation is a bank to a cashier or an assistant cashier;
• to any natural person designated by it as agent for the service of process; or
• if the corporation has designated a corporate agent, to any person named in the latest certificate of the corporate agent filed pursuant to Section 1505.

Cal. Corp. Code § 2110. The statute further provides that a copy of the statement and designation, or a copy of the latest statement filed pursuant to Corporations Code Section 2117, certified by the Secretary of State, is sufficient evidence of the appointment of an agent for the service of process.