Cold Email Rules for 2026: How to Reach New Customers Without Burning Your Domain
Gmail’s sender rules and the CAN-SPAM Act set the limits for business email. Here is what they require and how to send outreach that stays out of spam.
The short answer
Your email domain is an asset, and cold outreach can damage it fast. Gmail requires every sender to set up email authentication and to keep reported spam below 0.3% (Google Workspace Admin Help). U.S. law adds its own rules: a working opt-out, your physical address, and honest subject lines, with penalties of up to $53,088 per email that breaks them (FTC). Send fewer, better emails, and have a person approve them.
What Gmail requires
From Google’s sender guidelines:
- Everyone: set up SPF or DKIM authentication for your sending domain, and keep spam rates in Google Postmaster Tools below 0.3%.
- Senders of more than 5,000 messages a day to Gmail: set up SPF, DKIM and DMARC, and make marketing emails support one-click unsubscribe with a visible unsubscribe link.
What the law requires
From the FTC’s CAN-SPAM guide, commercial email must:
- Use honest From lines and subject lines
- Include a valid physical postal address
- Tell people how to opt out, and honor opt-outs within 10 business days
The rules cover business-to-business email too.
How to send outreach safely
- Use a separate sending domain for cold outreach, so a problem there doesn’t hurt the email your customers rely on.
- Set up SPF, DKIM and DMARC before the first email goes out.
- Start with a small number each day and raise it slowly. Watch bounces and spam complaints as you go.
- Verify every address before you send. Bounces hurt your sender reputation.
- Write to one person about one thing. Name their company and why you’re writing to them in particular.
- Have a person approve every batch. Software can find companies and draft emails. A person should check the list and the wording before anything goes out.
- Keep a do-not-contact list and check it before every send.
FAQ
Is cold email legal?
In the U.S., yes, as long as it follows CAN-SPAM: honest headers and subject lines, a physical address and a working opt-out (FTC). Other countries have stricter rules.
How do I know if my domain is in trouble?
Watch your spam rate in Google Postmaster Tools. Gmail’s line is 0.3% (Google Workspace Admin Help).
Sources: Google Workspace Admin Help: Email sender guidelines · FTC CAN-SPAM Act compliance guide