You do not have a legal right to require someone to refrain from communicating with you, unless a legal protection order, restraining order, or injunction bars them from doing so (with narrow exceptions not applicable here, such as certain spam marketing communications, or communications by lawyers with people represented by counsel, or communications from law enforcement while you are in custody after you have requested a lawyer).
Sending a cease and desist letter is merely a request. It is not legally binding. Communicating with someone despite a cease and desist letter from them is rude but not illegal.
No contact orders can only be issued by courts for quite extreme conduct, although the exact standard varies from state to state. The availability of no contact orders is further limited by federal first amendment limitations. The fact that contact from someone is merely unwanted or annoying or rude is not an adequate basis for a court to issue a no contact order.
Also, the fact that you have not sent someone a cease and desist letter does not prohibit a court from entering a no contact order. Sometimes a cease and desist letter and continued contact after it is sent could be one factor among many that would be considered by a court issuing a no contact order, but it is neither necessary, nor sufficient, for a court to issue a no contact order.
In situations where it is helpful to have asked someone to cease and desist, telling someone "leave me alone, stop contacting me" is every bit as effective for the purposes of obtaining a no contact order as a more formally drafted letter from a lawyer. But, if you contact them despite telling them no to contact you, that undermines the evidentiary value of a cease and desist letter, or a less formal communication to the same effect.
For example, in Colorado, to obtain a temporary protection order (which is a prerequisite for a permanent one) outside the context of a criminal case or domestic relations lawsuit, one must show that you need it in order to:
(I) To prevent assaults and threatened bodily harm;
(II) To prevent domestic abuse;
(III) To prevent emotional abuse of the elderly or of an at-risk
(IV) To prevent sexual assault or abuse; and
(V) To prevent stalking.
Colorado Revised Statutes § 13-14-104.5(1)(a).
Some key terms in that part of the statute are defined as follows:
(1) “Abuse of the elderly or of an at-risk adult” means mistreatment
of a person who is sixty years of age or older or who is an at-risk
adult as defined in section 26-3.1-101(1.5), including but not limited
to repeated acts that:
(a) Constitute verbal threats or assaults;
(b) Constitute verbal harassment;
(c) Result in the inappropriate use or the threat of inappropriate use
(d) Result in the inappropriate use of physical or chemical
(e) Result in the misuse of power or authority granted to a person
through a power of attorney or by a court in a guardianship or
conservatorship proceeding that results in unreasonable confinement or
restriction of liberty; or
(f) Constitute threats or acts of violence against, or the taking,
transferring, concealing, harming, or disposing of, an animal owned,
possessed, leased, kept, or held by the elderly or at-risk adult,
which threats or acts are intended to coerce, control, punish,
intimidate, or exact revenge upon the elderly or at-risk adult.
(1.5) “Adult” means a person eighteen years of age or older.
(1.7) “Contact” or “contacting” means any interaction or communication
with another person, directly or indirectly through a third party, and
electronic and digital forms of communication, including but not
limited to interaction or communication through social media.
(2) “Domestic abuse” means any act, attempted act, or threatened act
of violence, stalking, harassment, or coercion that is committed by
any person against another person to whom the actor is currently or
was formerly related, or with whom the actor is living or has lived in
the same domicile, or with whom the actor is involved or has been
involved in an intimate relationship. A sexual relationship may be an
indicator of an intimate relationship but is never a necessary
condition for finding an intimate relationship. For purposes of this
subsection (2), “coercion” includes compelling a person by force,
threat of force, or intimidation to engage in conduct from which the
person has the right or privilege to abstain, or to abstain from
conduct in which the person has a right or privilege to engage.
“Domestic abuse” may also include any act, attempted act, or
threatened act of violence against:
(a) The minor children of either of the parties; or
(b) An animal owned, possessed, leased, kept, or held by either of the
parties or by a minor child of either of the parties, which threat,
act, or attempted act is intended to coerce, control, punish,
intimidate, or exact revenge upon either of the parties or a minor
child of either of the parties.
(2.2) “Minor child” means a person under eighteen years of age.
(2.3) “Protected person” means the person or persons identified in a
protection order as the person or persons for whose benefit the
protection order was issued.
(2.4)(a) “Protection order” means any order that prohibits the
restrained person from contacting, harassing, injuring, intimidating,
molesting, threatening, touching, stalking, or sexually assaulting or
abusing any protected person or from entering or remaining on
premises, or from coming within a specified distance of a protected
person or premises, or from taking, transferring, concealing, harming,
disposing of or threatening harm to an animal owned, possessed,
leased, kept, or held by a protected person, or any other provision to
protect the protected person from imminent danger to life or health
that is issued by a court of this state or a municipal court and that
is issued pursuant to:
(I) This article 14, section 18-1-1001, 19-2.5-607, or 19-4-111, or
rule 365 of the Colorado rules of county court civil procedure;
(II) Sections 14-4-101 to 14-4-105, C.R.S., section 14-10-107, C.R.S.,
section 14-10-108, C.R.S., or section 19-3-316, C.R.S., as those
sections existed prior to July 1, 2004;
(III) An order issued as part of the proceedings concerning a criminal
municipal ordinance violation; or
(IV) Any other order of a court that prohibits a person from
contacting, harassing, injuring, intimidating, molesting, threatening,
touching, stalking, or sexually assaulting or abusing a person, or
from entering or remaining on premises, or from coming within a
specified distance of a protected person or premises, or from taking,
transferring, concealing, harming, disposing of or threatening to harm
an animal owned, possessed, leased, kept, or held by a person, or from
entering or remaining on premises, or from coming within a specified
distance of a protected person or premises.
(b) For purposes of this article only, “protection order” includes any
order that amends, modifies, supplements, or supersedes the initial
protection order. “Protection order” also includes any emergency
protection order, as described in section 13-14-103, any restraining
order entered prior to July 1, 2003, and any foreign protection order
as defined in section 13-14-110.
(2.8) “Restrained person” means a person identified in a protection
order as a person prohibited from doing a specified act or acts.
(2.9) “Sexual assault or abuse” means any act, attempted act, or
threatened act of unlawful sexual behavior, as described in section
16-11.7-102(3), C.R.S., by any person against another person
regardless of the relationship between the actor and the petitioner.
(3) “Stalking” means any act, attempted act, or threatened act of
stalking as described in section 18-3-602, C.R.S.
Colorado Revised Statutes § 13-14-104.
Realistically, this question is talking about alleged stalking which is defined as follows:
(1) A person commits stalking if directly, or indirectly through
another person, the person knowingly:
(a) Makes a credible threat to another person and, in connection with
the threat, repeatedly follows, approaches, contacts, or places under
surveillance that person, a member of that person's immediate family,
or someone with whom that person has or has had a continuing
(b) Makes a credible threat to another person and, in connection with
the threat, repeatedly makes any form of communication with that
person, a member of that person's immediate family, or someone with
whom that person has or has had a continuing relationship, regardless
of whether a conversation ensues; or
(c) Repeatedly follows, approaches, contacts, places under
surveillance, or makes any form of communication with another person,
a member of that person's immediate family, or someone with whom that
person has or has had a continuing relationship in a manner that would
cause a reasonable person to suffer serious emotional distress and
does cause that person, a member of that person's immediate family, or
someone with whom that person has or has had a continuing relationship
to suffer serious emotional distress. For purposes of this paragraph
(c), a victim need not show that he or she received professional
treatment or counseling to show that he or she suffered serious
(2) For the purposes of this part 6:
(a) Conduct "in connection with" a credible threat means acts that
further, advance, promote, or have a continuity of purpose, and may
occur before, during, or after the credible threat.
(b) "Credible threat" means a threat, physical action, or repeated
conduct that would cause a reasonable person to be in fear for the
person's safety or the safety of his or her immediate family or of
someone with whom the person has or has had a continuing relationship.
The threat need not be directly expressed if the totality of the
conduct would cause a reasonable person such fear.
(c) "Immediate family" includes the person's spouse and the person's
parent, grandparent, sibling, or child.
(d) "Repeated" or "repeatedly" means on more than one occasion.
Colorado Revised Statutes § 18-3-602 (in the pertinent part).
In the facts of this question, stalking under C.R.S. § 18-3-602(1)(c) is the key point. But the scope of C.R.S. § 18-3-602(1)(c) has been recently narrowed by the U.S. Supreme Court case of Counterman v. Colorado, 600 U. S. ____, which was decided on June 27, 2023. This case held that to criminally prosecute someone for stalking based upon a "true threat" that the prosecution must show that the alleged stalker intended the communication to be a true threat, knew that it was understood to be a true threat, or that the alleged stalker made the communication recklessly knowing that it might be understood as a true threat. As the official syllabus of the opinion explains:
From 2014 to 2016, petitioner Billy Counterman sent hundreds of
Facebook messages to C. W., a local singer and musician. The two had
never met, and C. W. did not respond. In fact, she tried repeatedly to
block him, but each time, Counterman created a new Facebook account
and resumed contacting C. W. Several of his messages envisaged violent
harm befalling her. Counterman’s messages put C. W. in fear and
upended her daily existence: C. W. stopped walking alone, declined
social engagements, and canceled some of her performances. C. W.
eventually contacted the authorities. The State charged Counterman
under a Colorado statute making it unlawful to “[r]epeatedly . . .
make any form of communication with another person” in “a manner
that would cause a reasonable person to suffer serious emotional
distress and does cause that person . . . to suffer serious emotional
distress.” Colo. Rev. Stat. §18–3–602(1)(c). Counterman moved to
dismiss the charge on First Amendment grounds, arguing that his
messages were not “true threats” and therefore could not form the
basis of a criminal prosecution. Following Colorado law, the trial
court rejected that argument under an objective standard, finding that
a reasonable person would consider the messages threatening.
Counterman appealed, arguing that the First Amendment required the
State to show not only that his statements were objectively
threatening, but also that he was aware of their threatening
character. The Colorado Court of Appeals disagreed and affirmed his
conviction. The Colorado Supreme Court denied review.
Held: The State must prove in true-threats cases that the defendant
had some subjective understanding of his statements’ threatening
nature, but the First Amendment requires no more demanding a showing
than recklessness. Pp. 4–14.
(a) The First Amendment permits restrictions upon the content of
speech in a few limited areas. Among these historic and traditional
categories of unprotected expression is true threats. True threats
are “serious expression[s]” conveying that a speaker means to “commit
an act of unlawful violence.” Virginia v. Black, 538 U. S. 343, 359.
The existence of a threat depends not on “the mental state of the
author,” but on “what the statement conveys” to the person on the
receiving end. Elonis v. United States, 575 U. S. 723, 733. Yet the
First Amendment may still demand a subjective mental-state requirement
shielding some true threats from liability. That is because bans on
speech have the potential to chill, or deter, speech outside their
boundaries. An important tool to prevent that outcome is to condition
liability on the State’s showing of a culpable mental state. Speiser
v. Randall, 357 U. S. 513, 526. That kind of “strategic protection”
features in this Court’s precedent concerning the most prominent
categories of unprotected speech. Gertz v. Robert Welch, Inc., 418 U.
S. 323, 342. With regard to defamation, a public figure cannot
recover for the injury such a statement causes unless the speaker
acted with “knowledge that it was false or with reckless disregard of
whether it was false or not.” New York Times Co. v. Sullivan, 376 U.
S. 254, 280. The same idea arises in the law respecting obscenity and
incitement to unlawful conduct. See, e.g., Hess v. Indiana, 414 U. S.
105, 109; Hamling v. United States, 418 U. S. 87, 122–123. And that
same reasoning counsels in favor of requiring a subjective element in
a true-threats case. A speaker’s fear of mistaking whether a
statement is a threat, fear of the legal system getting that judgment
wrong, and fear of incurring legal costs all may lead a speaker to
swallow words that are in fact not true threats. Insistence on a
subjective element in unprotected-speech cases, no doubt, has a cost:
Even as it lessens chill of protected speech, it makes prosecution of
otherwise proscribable, and often dangerous, communications harder.
But a subjective standard is still required for true threats, lest
prosecutions chill too much protected, non-threatening expression.
(b) In this context, a recklessness standard—i.e., a showing that a
person “consciously disregard[ed] a substantial [and unjustifiable]
risk that [his] conduct will cause harm to another,” Voisine v. United
States, 579 U. S. 686, 691—is the appropriate mens rea. Requiring
purpose or knowledge would make it harder for States to counter true
threats—with diminished returns for protected expression. Using a
recklessness standard also fits with this Court’s defamation
decisions, which adopted a recklessness rule more than a half-century
ago. The Court sees no reason to offer greater insulation to threats
than to defamation. While this Court’s incitement decisions demand
more, the reason for that demand—the need to protect from legal
sanction the political advocacy a hair’s-breadth away from
incitement—is not present here. For true threats, recklessness
strikes the right balance, offering “enough ‘breathing space’ for
protected speech,” without sacrificing too many of the benefits of
enforcing laws against true threats. Elonis, 575 U. S., at 748. Pp.
(c) The State prosecuted Counterman in accordance with an objective
standard and did not have to show any awareness on Counterman’s part
of his statements’ threatening character. That is a violation of the
First Amendment. P. 14.
A cease and desist letter could clarify for the unwanted communicator that the communications are actually causing serious emotional harm, in the fact of a claim of obliviousness, although prior verbal communications could also show the requisite intent (and would probably be more powerful evidence). But this intention to harm that amounts to serious emotional distress must be objectively very extreme to meet this standard, regardless of the person's intentions. And, intent to annoy or manipulate or make unwanted communications isn't sufficient. Counterman illustrates the kind of fact pattern that is sufficiently extreme to pass constitutional muster.
The availability of a no contact order is a fact intensive and jurisdiction specific question. It can't be answered from the facts in the question alone.