Email marketing rules allow you to message people who gave you consent, and your own customers if you offer similar goods or services and include an easy unsubscribe option in every email. To keep messages out of spam, your domain needs SPF, DKIM, and DMARC records.

Email is the cheapest way to reach customers who already know you, provided you write legally and land in their inbox. For Czech inboxes, both areas are shifting: the Chamber of Deputies passed a new Digital Economy Act, and mailbox providers tightened bulk-sending rules (in Czechia, Seznam sets the pace). Here we combine legal compliance and technical setup into one workflow as of November 13, 2026. This text does not replace legal advice.

Email marketing rules: who you can contact

You always need prior consent for commercial emails unless you are writing to an existing customer about your own similar products. In Czechia, this is set by Section 7 of Act No. 480/2004 Coll. Any message that directly or indirectly promotes sales or your company's image counts as a commercial communication, including a tips newsletter.

The customer exemption has four conditions:

• you obtained the contact from a sale of goods or services,
• you offer your own similar products,
• the customer had a free, simple way to refuse marketing when giving the address and did not,
• every subsequent message includes an easy way to unsubscribe.

The Czech Office for Personal Data Protection (ÚOOÚ) clarifies in its FAQ that a customer is someone who entered into a contract with your company (paid or free), not merely a contest entrant or a prospect.

Example: A fictional online bakery sells cakes. It may offer Christmas cookies (similar goods) without consent to a customer who bought a birthday cake, but not partner insurance. It may email a cake-contest entrant only with consent.

Every email must also meet three formal requirements under Section 7(4):

• clear labeling as a commercial communication,
• clear identity of the sender,
• a valid contact for direct and effective opt-out.

ÚOOÚ recommends confirming newsletter sign-ups by email (double opt-in). The sender bears the burden of proof and must prove consent if a recipient complains.

Consent that holds up

Under GDPR, marketing consent must be freely given, specific, informed, and unambiguous. Use a separate, unticked checkbox outside your terms and conditions. State what you send and how often, and link to your privacy notice. Purchased lists and blanket consent for "all partners" will not hold up.

What the Czech Digital Economy Act changes

Czechia's new Digital Economy Act limits the customer exemption to two years from the last commercial email. The Chamber of Deputies passed it on November 4, 2026. According to a summary by Sedláková Legal from November 11, 2026, it still awaits the Senate and presidential signature, taking effect fifteen days after publication in the Collection of Laws to replace Act No. 480/2004 Coll.

Core rules and ÚOOÚ oversight stay in place, while fines increase and the two-year cap applies. Under the approved draft, the period will not expire earlier than two years after the Act takes effect, leaving time to prepare.

The Senate may still amend the wording (the table reflects November 13, 2026). Because the two-year clock runs from the last message, it mainly affects businesses reviving dormant contacts after years of silence.

Before the Act takes effect, we recommend three steps:

• record each contact's legal basis and the date of the last commercial email,
• review old customer lists and decide whether to email them regularly or remove them,
• track the Senate vote and the effective date.

Step-by-step contact list audit

Auditing your list prepares you for the new law and improves deliverability. With a spreadsheet from your email tool, you can finish it in an afternoon:

1. Export all contacts from your email platform, online store, and accounting system, including acquisition date and source.
2. Sort them by legal basis: consent (when, where, and with what wording), customer (when and what they bought), and no basis.
3. Stop sending marketing emails to contacts with no basis. These include addresses from business cards, trade fairs, contests, and public sources without consent. Keep them in your system if needed for invoicing or contracts, but exclude them from campaigns.
4. Add the date of the last commercial email and set it to log automatically.
5. Save proof of consent: date, form, wording, and opt-in confirmation.
6. Check your templates: commercial label, clear sender, and working unsubscribe link in every message.
7. Clean out inactive and undeliverable addresses. Non-existent mailboxes and contacts silent for years hurt your reputation with inbox providers.

An audit brings commercial gains too. A smaller list of engaged readers means fewer spam complaints and better inbox placement. Repeat purchases from email also cost nothing in extra ad spend; see how we calculate acquisition cost in Customer acquisition cost.

Why emails go to spam: SPF, DKIM, and DMARC explained

Emails mostly land in spam when the recipient's inbox cannot verify that your company sent them. Domain DNS records—SPF, DKIM, and DMARC—handle this verification. When they are missing or misconfigured, the inbox treats your message as a potential fake.

Think of a physical letter:

• SPF lists the post offices allowed to send your mail.
• DKIM is a signature and seal proving the letter is genuine and unaltered in transit.
• DMARC tells the recipient's mailroom whether to accept, quarantine, or reject unverified mail, and reports attempts to spoof your name.

Setups often break when you change your newsletter tool, e-commerce platform, or mail server. If you do not add the new service to SPF and set up DKIM, messages leave from a server your domain does not recognize. Check that your records include every sending service after each change.

Roll out DMARC gradually:

1. Start in monitoring mode (p=none) and watch for several weeks which services send mail for you and whether they pass checks.
2. Once all legitimate messages pass, switch to quarantine (p=quarantine) or rejection (p=reject). Moving too early can block your own invoices or order confirmations.

Since February 1, 2024, Gmail requires all senders to use at least SPF or DKIM and keep spam rates below 0.3% (under 0.1% recommended). Sending 5,000 or more messages a day to Gmail requires SPF, DKIM, and DMARC, sender domain alignment with SPF or DKIM, and one-click unsubscribe in marketing emails.

DMARC also stops scammers from sending fake invoices under your company's name. We cover further defenses in Cybersecurity for businesses.

Why Seznam rules matter when emailing Czech customers

In Czechia, Seznam largely decides inbox placement. In a February 2025 analysis of 5,404,024 client mailboxes from December 2024, agency Etnetera Activate found Seznam held 64.5%, Gmail 24.2%, and Centrum 5.6%.

In its bulk-sender guidelines, Seznam requires valid SPF (covering all sending servers) and DKIM records; without them, emails go to spam or never arrive. It strongly recommends DMARC, noting that it is becoming mandatory worldwide.

Providers also track clicks on "Report spam." Write only to people who want to hear from you, and make the unsubscribe link easy to find—anyone who cannot spot it will mark the email as spam.

What to send so people open your emails

People open emails that help them and match their purchases. A steady schedule and interest-based segments work better than discounts for everyone.

Welcome series

Send an automated sequence right after sign-up. Thank the subscriber, confirm how often you write, and share your best content in the first email, then introduce your business and answer common questions.

Post-purchase care and reviews

Follow a purchase with a how-to guide and ask for a review later. A fictional cosmetics shop might send cream-application tips after a week and a review link a week later. Under ÚOOÚ guidance, a review request is also a commercial communication and follows the same rules as a newsletter. Read more in Google reviews and Abandoned cart.

Useful content over discounts

Constant discounts train customers to wait for a sale. Send guides, comparisons, seasonal tips, or new arrivals instead. A fictional joinery could send monthly wood-care tips and a new collection once a quarter.

Frequency and segments

State how often you will write at sign-up and stick to it. Segment contacts by interest and separate buyers from non-buyers. This keeps spam reports down.

Paid marketing campaigns bring in new customers, and email brings them back. We are happy to help configure your domain or owned channels—contact us.

Frequently asked questions