Email Marketing Essentials: Newsletters, Transactional Emails and Reaching the Inbox

Email is one of the few channels you own. No social media algorithm decides whether your subscribers see your message, but mailbox providers do decide whether it lands in the inbox, a promotions tab or spam. Many businesses that rely on Instagram and WhatsApp leave email underused. That is a missed opportunity, and starting correctly is not difficult.

Two kinds of email, two sets of rules

Marketing emails (newsletters, promotions, product announcements, content digests) go to many people at once and require consent. Recipients can live without them, so every message has to earn attention.

Transactional emails are triggered by a person's action or account: order confirmations, password resets, invoices, delivery notices, booking reminders. People expect them and often need them. They must be fast, clear and reliable.

Keep the two apart technically. Many companies send marketing and transactional mail from separate subdomains or sending streams, for example news.yourbrand.com and mail.yourbrand.com. If a campaign triggers spam complaints, your password resets and invoices should not suffer. Do not turn transactional emails into promotions either: a short, relevant recommendation is fine, a full sales newsletter is not.

Build the list the right way

• Collect addresses with clear consent: website forms, an opt-in at checkout, events, in-store sign-up. Say what people will receive and how often.
• Never buy or scrape lists. Purchased addresses bring spam complaints, spam traps and bounces, all of which damage your domain's reputation.
• Consider double opt-in (a confirmation email) for newsletter sign-ups. It keeps typos and fake addresses out.
• Follow the data protection rules that apply to you and your subscribers: your own country's law, and stricter regimes such as the EU's GDPR if you have subscribers there.

Deliverability basics

Deliverability is whether your email reaches the inbox. Since 2024, the largest mailbox providers have turned several best practices into requirements.

According to Gmail's sender guidelines, everyone who sends to Gmail accounts needs SPF or DKIM authentication and must keep the spam rate reported in Postmaster Tools below 0.3%. Senders of 5,000 or more messages a day must set up SPF, DKIM and DMARC, and their marketing messages must support one-click unsubscribe and include a visible unsubscribe link. Google recommends keeping the spam rate below 0.1%. Yahoo has similar requirements and asks bulk senders to honour unsubscribe requests within two days. Microsoft announced requirements for high-volume senders to Outlook.com, Hotmail and Live addresses in 2025.

What these terms mean in practice:

• SPF lists the servers that are allowed to send email for your domain.
• DKIM adds a digital signature that shows the message came from your domain and was not changed on the way.
• DMARC tells receiving servers what to do when SPF or DKIM checks fail, and sends you reports.
• One-click unsubscribe lets people leave your list with one action from the inbox, instead of marking you as spam.

Your email platform or IT team can set these records up in your domain's DNS. If you send from a free mailbox address, you cannot authenticate your messages properly, so always send from your own domain.

Beyond authentication:

1. Warm up a new domain or IP address: start with your most engaged contacts and increase volume gradually.
2. Clean your list: remove hard bounces immediately and stop mailing people who have not opened or clicked for a long time.
3. Watch complaints: a sudden rise usually means the wrong audience, the wrong frequency or the wrong content.
4. Monitor your reputation in Google Postmaster Tools and in your email platform's reports.

Write emails people want to open

• A sender name people recognise: the brand, or a person plus the brand.
• A specific, honest subject line. Clickbait raises opens once and complaints for a long time.
• One main message and one main button per email.
• Design for phones first: short paragraphs, large buttons, readable fonts.
• A plain-text version and alt text for images, because some email apps do not load images by default.
• Language choice at sign-up. In multilingual markets, let subscribers choose a language instead of putting three languages into one email.

Measure what matters

Open rates are less reliable than they used to be. Apple's Mail Privacy Protection downloads remote content in the background by default, regardless of whether the person engages with the email, so some recorded "opens" are not real reads. Focus on clicks, conversions, revenue or leads per email, the unsubscribe rate and spam complaints. Compare results with your own history rather than with industry averages from other markets.

Pre-send checklist

1. The segment includes only people who agreed to receive this type of email.
2. The sender name, reply-to address and domain are correct, and SPF, DKIM and DMARC pass.
3. The subject line and preview text are clear and match the content.
4. All links work, UTM parameters are set and the main button is visible on a phone.
5. The unsubscribe link and one-click unsubscribe work, and the footer shows your company name and contact details.
6. Test emails have been checked in Gmail, Outlook and on a phone.
7. The send time suits your audience's time zone.

In my experience, a clean, permission-based list and regular, useful emails work far better than occasional mass mailings. This week, check your authentication, separate your transactional and marketing streams, and save the checklist above for every send.