How to keep your marketing emails out of spam

What Gmail and Outlook do with your emails

• Gmail: Google runs automated checks to detect spam, viruses and other risks. It stopped scanning emails for personalised ads back in 2017, but its filters are as sharp as ever.
• Outlook: Microsoft puts the emphasis on privacy and does not scan emails for advertising either. It does check closely for spam and suspicious content.

Both also sort incoming mail on behalf of the user, so even an email that avoids the spam folder still has to earn its place where people actually look. That affects whether your marketing emails get seen and opened.

Why emails end up in spam

Emails are usually filtered out when:

• Authentication is missing: without the right settings, mailbox providers see you as less trustworthy.
• Recipients complain: a lot of spam reports damages your reputation.
• The content looks suspicious: words like “FREE!” or a row of exclamation marks trigger filters.
• Technical settings are wrong: think of errors in your sending domain or missing verification.

The technical baseline since 2024

Authentication is no longer a nice extra. Since February 2024, Gmail and Yahoo have required anyone sending around 5,000 or more emails a day to their users to:

• set up SPF and DKIM for the sending domain;
• publish a DMARC policy (at least “p=none”) that aligns with the From address;
• offer one-click unsubscribe in marketing emails and process unsubscribe requests within two days;
• keep the spam complaint rate below 0.3%, and ideally under 0.1%.

Gmail has been enforcing these rules more strictly since late 2025, with non-compliant mail delayed or rejected. Microsoft followed in May 2025: high-volume senders to Outlook.com, Hotmail and Live addresses must pass SPF, DKIM and DMARC, or their messages are rejected. Smaller senders face a lighter version (Gmail still expects SPF or DKIM and a low spam rate from everyone), and the same signals decide where their mail lands.

Getting this right is mostly a one-time job for your IT team or your marketing automation partner. Keeping your reputation is the part that never stops, and that is where the habits below come in.

Five habits that keep you in the inbox

At Pebble we believe respect for your customers and compliance go hand in hand with results. These five practical tips make your email marketing more privacy-friendly, and mailbox providers notice the difference.

1. Transparency above all

In a world where privacy matters more and more, transparency is the foundation of trust. If you are clear and honest about what you do with your customers’ data, you lay a solid base for the relationship and you meet the requirements of privacy law such as the GDPR.

Customers want to know where they stand. Being open about what you collect and how you use it shows that you respect their privacy. That builds trust, makes people more likely to subscribe and to stay engaged, and reduces the chance of complaints.

• Plain language: explain in simple words what data you collect and why. Skip the legal jargon. A short line on your sign-up form does the job: “We use your email address to keep you up to date on our latest offers and tips. You can unsubscribe at any time.”
• A clear privacy statement: make it easy to find, for example through a link on your sign-up form or website. Explain which data you collect, how you use it (for personalised offers, say), how long you keep it and who you share it with (such as external marketing tools).
• Double opt-in: send new subscribers an email to confirm their sign-up. It proves someone chose your communication on purpose, and it stops people being added to your list by accident or without knowing.

2. Say no to data hunger

It is tempting to collect as much information as possible. But more data does not automatically mean more success. Focusing on what you really need is more effective and more privacy-friendly. Every extra question on your sign-up form raises the chance that someone gives up.

Customers are increasingly critical about what they share. If it feels like you are asking too much, you lose their trust before the relationship has started. Unnecessary data also brings extra risk, such as data breaches or compliance problems.

• Decide what is essential: for every form field, ask yourself: Do I really need this to offer value? Do I actually use it in my marketing or analysis? Could I reach my goal without asking?
• Trim your forms: keep your sign-up form as short and simple as possible. A compact form lowers the threshold and raises your conversion rate.
• Less data, less risk: the less you collect, the smaller the chance of breaches or privacy complaints, and the simpler your data protection becomes.

3. Give control back to your customer

One of the pillars of a good email strategy is respecting your customers’ wishes. Let them decide what they receive, when and how often. Your emails stay relevant, so they get opened, and you show that you value people’s time and attention.

• Introduce a preference centre: one place where customers manage their email settings, such as frequency, topics and language.
• Make unsubscribing easy: a clear, visible unsubscribe link is a legal requirement, and for bulk senders to Gmail and Yahoo a one-click unsubscribe is now mandatory as well. No hoops, no extra questions.

More control means more relevant emails, which leads to higher open and click rates. It also means fewer unsubscribes, because people adjust their settings instead of leaving. And it helps you meet the GDPR, which expects customers to be able to manage their communication preferences.

4. Cleaning up is not a punishment

A clean list is good for your statistics and for your relationship with your customers. A list full of inactive recipients drags down your open rates and your deliverability.

• Higher open rates: when your list consists of people who are genuinely interested, more of your emails get opened, and more of them land in the inbox instead of spam.
• Better deliverability: Gmail and Outlook use recipient engagement as a measure of relevance. An active list protects your sender reputation.
• Less irritation: removing inactive contacts means fewer emails to people who never wanted them.

Analyse your list regularly to spot inactive subscribers, for example people who have not engaged for six months, and try to win them back with a targeted reactivation campaign. Still no response? Do not be afraid to remove them. Plan this clean-up as a routine, every quarter for instance.

5. Compliance is an ongoing process

Privacy law keeps evolving with technology and with what consumers expect. The GDPR sets the core rules, and the ePrivacy rules on electronic marketing still apply through national law. The EU’s long-awaited ePrivacy Regulation was dropped by the European Commission in 2025, which shows how much this area keeps moving. Treat compliance as a continuous process, not a one-off exercise.

New interpretations, guidelines and stricter rules appear all the time. That can feel intimidating, but it is also an opportunity: an organisation that keeps up shows it is professional and ready for what comes next.

• Follow the right sources: keep an eye on official channels such as your national data protection authority (in Belgium, the Data Protection Authority) and sector associations.
• Invest in training: keep your team up to date with regular sessions on privacy and data protection.
• Work with experts: no specialist in-house? Bring in an outside adviser to review your policy and processes.

When in doubt, choose the most customer-friendly option. Be open about how you use data, ask for explicit consent even where the law is not entirely clear, and give customers easy access to view, change or delete their data. It lowers your legal risk and strengthens trust.

Good habits travel further

By being transparent, respecting privacy and sending content people value, you make sure your emails arrive, and you build a brand people are happy to hear from. Good marketing is not only about the message, but also about the moment it lands.

Want a second pair of eyes on your setup? Get in touch.