Drafting a document and serving it on another party is insufficient to legally prevent them from contacting you. To formally restrict someone's ability to contact you, you'd need to petition the court for a restraining order, also known as a protection order. While private parties can mutually agree to a no-contact arrangement and seek court approval for it, this doesn't appear to be your intended course of action. For further details, consult our article on "How to Get a Civil Protection Order or No-Contact Agreement."
To answer your question, in Colorado, the rules governing service of process are primarily outlined in the Colorado Rules of Civil Procedure (C.R.C.P.), specifically Rule 4. Most cases begin with personal service as outlined below.
Personal Service: Hand-delivering the summons and complaint to the defendant.
Substituted Service: Delivering the documents to someone else at the defendant's residence, followed by mailing a copy to the defendant.
Service by Mail: Sending the documents via registered or certified mail with return receipt requested.
Service by Publication: Used as a last resort when the defendant cannot be located, this involves publishing the summons in a newspaper.
A sheriff, deputy sheriff, or private process server over the age of 18 and not a party to the case can serve the documents.