Email marketing

Email marketing is a business sending emails to people who agreed to receive them, to introduce products, look after customers or bring them back to buy again. An email list is a channel the business owns, so there is no per-impression cost like there is with ads.

What is email marketing?

An email marketing program needs a recipient list, content and sending software (an ESP, or email service provider) that tracks open rates, click rates and unsubscribes. Common types of email:

• Newsletters sent on a regular schedule.
• Promotional emails for each sale.
• Automated sequences: welcoming new subscribers, reminding people about abandoned carts, inviting past buyers back. This part falls under marketing automation.

Build the list yourself through sign-up forms, member accounts and orders, and keep it alongside purchase history in your CRM.

Rules for promotional email in Vietnam

Decree 91/2020/ND-CP on combating spam messages, spam emails and spam calls took effect on October 1, 2020. A promotional email sent without the recipient’s prior consent counts as spam (Article 3). The main provisions (Decree 91/2020/ND-CP, Vietnam Government Portal, August 2020):

• Send only to people who consented in advance, for example through a sign-up form on a website, app or social network. Records of sign-ups and refusals must be kept for at least 1 year (Article 11).
• No more than 3 promotional emails to one email address within 24 hours, unless you have a different agreement with the recipient (Article 13).
• Put the label [QC] or [AD] at the very start of the subject line (Article 18).
• Show the advertiser’s name, phone number, email and address directly above the opt-out section (Article 19).
• Place the opt-out section at the end of the email, and let people opt out via a website or social network, by email and by phone. When a request arrives, send a confirmation right away and stop sending (Article 20).

A customer’s email address is personal data, so Vietnam’s Personal Data Protection Law No. 91/2025/QH15 also applies (see our guide to Vietnam’s personal data protection law for marketers).

Gmail and Yahoo rules for bulk senders

Since February 1, 2024, anyone sending more than 5,000 emails a day to personal Gmail accounts must authenticate their domain with SPF, DKIM and DMARC and keep the spam rate reported in Postmaster Tools below 0.3%. Marketing emails must support one-click unsubscribe and include a clearly visible unsubscribe link in the body (Google, Email sender guidelines, accessed October 2026).

The 5,000 threshold counts all mail sent from the same primary domain. Google recommends handling unsubscribe requests within 48 hours (Google, Email sender guidelines FAQ, accessed October 2026). Yahoo has similar requirements and states that unsubscribes should be honored within 2 days (Yahoo Sender Hub, Best practices, accessed October 2026).

Illustrative example (hypothetical)

A fashion shop has 10,000 subscribers. Each sale newsletter gets 2% of recipients to click through to the site (200 people), and 5% of those buy (10 orders) at an average of VND 500,000. Each send brings in 10 x 500,000 = VND 5 million, so 4 newsletters a month bring in VND 20 million against VND 1.5 million in software costs.

Email marketing vs transactional email vs spam

To message customers on Zalo (a Vietnamese messaging app) instead of email, see ZNS (Zalo Notification Service).

Frequently asked questions

Can I buy an email list and send to it?

You shouldn’t. Decree 91/2020 requires advertisers to be able to verify each recipient’s prior consent. Purchased lists almost never come with that proof.

Do emails to past customers need the [QC] label?

An email that introduces products or promotions is a promotional email under Article 3, so it still needs the label even if the recipient has bought from you before.

If you need to set up email capture from ads and measure all the way to orders, see Adtek’s Lead Generation page.