Guide
Is B2B cold email legal in the US? What CAN-SPAM requires
The US lets you send the first email without consent, then sets firm rules for what it contains and how fast you stop.
Short answer
Yes, if the email follows CAN-SPAM. The law "makes no exception for business-to-business email" [1], but it does not require consent first. Each email needs an honest subject line [2], a clear sign that it is an advertisement [3], your valid physical postal address [4] and a way to opt out, honoured within 10 business days [5]. Penalties run up to $53,088 per email [6].
General information, not legal advice, as of the date above. Where a regulator says its guidance is under review, we say so. If your situation is unusual, ask a lawyer who practises in that country.
The rules, from the FTC
| Rule | What the FTC says |
|---|---|
| Honest subject line | "The subject line must accurately reflect the content of the message." [2] |
| Say it is an ad | "you must disclose clearly and conspicuously that your message is an advertisement", with "a lot of leeway in how to do this" [3] |
| Postal address | "Your message must include your valid physical postal address." [4] |
| Opt-out that keeps working | It must work "for at least 30 days after you send your message" [7] |
| Honour opt-outs | "within 10 business days" [5] |
The address question: you do not have to use your home
Founders working from home often stop here. The FTC says the address "can be your current street address, a post office box you've registered with the U.S. Postal Service, or a private mailbox you've registered with a commercial mail receiving agency established under Postal Service regulations" [8]. A registered PO box or a commercial mailbox works.
"Identify it as an ad" in a one-to-one email
The FTC leaves the wording to you [3]. In a short personal email, the honest way is to be plain about why you are writing: name your company and what you offer in the email itself, rather than dressing a sales email up as something else. A subject line that pretends to be a reply or an invoice breaks the subject line rule as well.
What the penalty means
"Each separate email in violation of the CAN-SPAM Act is subject to penalties of up to $53,088" [6]. The amount is per email and is adjusted for inflation, so check the FTC page for the current figure. At 50 emails a day, a missing address is not one mistake but fifty.
Checklist for each email
- A subject line that describes the email.
- Your name and company, and plainly what you are offering.
- Your postal address (street address, registered PO box or commercial mailbox).
- A way to opt out that works for at least 30 days, and opt-outs honoured well inside 10 business days.
- No selling or sharing the addresses of people who opted out.
How Honest Intros helps
Honest Intros will not send until your company profile has a postal address, and it adds that address to every email. Every email carries an unsubscribe link and one-click unsubscribe headers, and an opt-out stops all further email to that person straight away. How plainly the email says what you are offering is in your wording, which you approve before anything is sent.
Questions
Is cold email legal in the US?
Yes. CAN-SPAM does not require consent before the first email, but every commercial email must follow its rules, including for business-to-business email.
Can I use a PO box for CAN-SPAM?
Yes. The FTC accepts a post office box registered with the US Postal Service or a private mailbox registered with a commercial mail receiving agency.
How fast must I honour an unsubscribe under CAN-SPAM?
Within 10 business days, and the opt-out must keep working for at least 30 days after you send.
What is the CAN-SPAM penalty per email?
Up to $53,088 per email as of 1 October 2026, according to the FTC. The figure is adjusted for inflation.
See what it would write for you
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