Deliverability is the buzzword in the world of email marketing. But what does it really mean? Simply put: it is about whether your e-mails actually reach the recipient’s inbox. And that involves more than just a nice email template and a good subject line.
Delivery = When an email was successfully delivered to the provider’s mailbox, e.g. Gmail
Deliverability = When an email is successfully delivered to the recipient’s inbox, e.g. firstname@gmail.com
For marketers who have already mastered everything except deliverability: this blog will help you recognise the main pitfalls as well as give practical tips to improve your email performance. There is no one-size-fits-all answer to questions like ‘What is my send reputation?’ or ‘Why does my e-mail end up in the spam folder?’. It looks at the following 6 aspects:
6 key deliverability aspects
1. Authentication & sender settings
A good technical set-up is crucial. Domain authentication via SPF, DKIM and DMARC is no longer optional, but a must. And do you really want to do well? Go one step further. Read more about SPF, DKIM and DMARC in our earlier blog “Email technology in order: A must in the age of stricter email clients!“
Useful tips
- Check that your DMARC, DKIM and SPF are in order via the free tool EmailAnalyzer.
- Think about Apple Branded Mail (free) and BIMI for brand trust in the inbox. This is really low-hanging fruit that can really help you stand out in the short term. Check that your DMARC, DKIM and SPF are in order via the free EmailAnalyzer tool.
- Never send an email from a no-reply address, always give the recipient a chance to send a response.
- If you still email from an info@ e-mail address: change immediately to newsletter@ or first name@. Info@ mail addresses are really a red-flag for email clients.
- For opt-in mails, use a different template as well as a separate sender address such as optin@e.domein.nl.
2. Data quality is key!
A successful email campaign starts with a clean database. Always start with a clean slate when migrating from one email system to another. Going through your new signups regularly (at least weekly) is not a luxury. Watch out for weird email addresses like gmial.com, double @’s, commas instead of full stops or other unlikely domains. These kinds of addresses are often spam traps or simply entered incorrectly.
Useful tips
- Sending a double opt-in email is and remains best practice!
- Add to your sign-up form a real-time check such as: “Did you mean gmail.com?”
- Tools like Kickbox help you score email addresses for reliability. A score below 0.7? Don’t mail.
- Do you ever manually import an email list? Always put everything in lowercase in the import document. Elise@domein.nl and elise@domein.nl are otherwise seen as separate records.
- Check out the tool Kickbox: check email addresses before you use them.
- Also, add a CAPTCHA to your registration form. Or even better Cloudflare Turnstile to stop bots.
- Note that manually adjusting typos in email addresses is not allowed by law – even though it sometimes seems tempting.
3. Sending reputation: your digital credit rating
Mailbox providers such as Gmail and Outlook rate you as a sender in terms of IP and domain reputation. This reputation is determined by several factors such as bounce rates, spam complaints and engagement. The better your reputation, the more likely your mails will end up in the inbox. There is no single central point where you can view your sending reputation. If only it were that easy! Some email clients exchange information among themselves, but, for example, a Google only knows your reputation with the Gmail addresses. Now let Google be the e-mail client where you get the most transparency as an email marketer through the Google Postmasters tool. Within this tool, you can see whether you pass the spam and bounce bounds. This is a good reflection and insight into the quality of your database.
Blacklisting and delisting: Blacklisting means that your email server or domain will be blacklisted by spam filters or mailbox providers. This happens, for example, if you get too many spam complaints, or mail to bad or fake email addresses. If you are on such a list, your emails often do not arrive at all. Delisting is the process whereby you ask to be taken off such a list again and promise to get better. You will then be under heavy scrutiny for at least a month, so it is wise to only include newly registered email addresses in the initial period. After this period, you can gradually add the email addresses with the most interaction.
Note: some lists, such as Spamhaus, are highly influential and require active action. Others, such as Barracuda, may be outdated and less relevant.
Useful tips
- Make sure you regularly send emails to the free tool EmailAnalyzer. This will give you feedback on the severity of the email or individual images and whether you may be on a spam list. If you are on a spam list, pass this on to your Wander Journeys contact and we can take the next steps for you.
When sending from a new sending domain, it is best to have a warm-up plan ready. Start emailing the highest engagers and spread your sending volumes over several days and build up incrementally. Keep a close eye on bounce rates, open rates and complaints. Keep inactive email addresses out of the equation.
Google and Yahoo already have the rule that if you have sent 5,000 emails or more per day ever you will be labelled a “bulk sender”, putting you under an extra magnifying glass. Microsoft has announced it will also tighten their policy in this way from 5 May 2025. Microsoft accounts are email addresses with extensions such as @outlook @live and @hotmail.
- Make use of Google Postmasters Tool (GPM) – a tool that gives you insight into spam and bounce rates. Make sure you get below 0.3%, in GPM that is a very clear red line.
- Greylisting can cause delayed delivery of your email, as the email client is still a little unsure whether your mail should really be delivered to the inbox. So don’t be shocked by late bounces, for example, 48 hours after sending, and don’t cheer too soon immediately after sending either. Do the reporting of your email at least 3 days after sending.
4. Policies
Each email client (Gmail, Yahoo etc.) has its own policies when it comes to sender reputation. However, we do know that a high bounce and spam ratio are not favourable for your sending reputation.
Interaction: not a monologue but dialogue
Mailbox providers are paying more and more attention to engagement. Not just whether it is opened, but how quick and whether there is interaction. Mails that are only opened after three days? Those hardly help your reputation.
This is how you improve engagement:
- Send emails to which you can really respond (reply-to to an active email address).
- Add buttons that prompt the reader to take action or feedback. Do not ask a question in the subject line ‘Have you booked your holiday yet?’ if you are not interested in the answer. Give the option in the mail for the recipient to reply via a ‘yes-no button’.
- Mail at least once a month to maintain your positive score.
- Set up a reactivation campaign that you run as automation every day (and not bulk mail inaction recipients twice a year). Inactives are recipients who have received a newsletter at least every month and have not shown engagement once in the past six months.
5. Quality of the email
A perfect email is relevant to the recipient, is opened quickly and invites interaction. The email is not too heavy (under 100 kb) has a good ratio of images to text. Make sure the images are not too heavy. Did you know that Google is going to roll out an update that sorts mail from most interactions to last received? Until now, Gmail by default sorted mails by last received. Microsoft will most likely follow soon. The faster you are opened (faster than others), the better for your reputation and the higher you get. When exactly this will be rolled out is still unknown.
Useful tips:
- Make sure it is easy to unsubscribe, preferably show this both at the top of the email, and at the bottom of the email.
- Make sure images are not too large. About 100-200 kb is a good average. Use the free tool TinyPNG to resize your images but not compromise on image quality.
- Use the free tool EmailAnalyzer, to receive feedback on the quality of your email.
- Make sure your email is no heavier than 100 Kb (bare HTML without including images), otherwise you will get point deductions in EmailAnalyzer. Once your email goes over 250 Kb, then the email will be clipped in Gmail and not shown in full.
6. Sending process
A stable infrastructure is crucial for a reliable sending process. Especially with high mail pressure and large volumes, your sending platform must be scalable and well-designed. Under time pressure, you often see campaigns being sent “just as quickly”, but this is precisely when errors occur that can damage your deliverability.
Useful tips:
Take into account sending windows, spread over time and the right timing per target group. Through smart segmentation and phased sending, you keep control over performance and maintain a good reputation.
- Sending windows are the predetermined time periods in which you send emails, for example:
– Between 08:00 and 18:00 on working days
– In batches of 5.000 per hour
– Or spread out over several days - The Throttle speed can be set in Deployteq: This can be the case with large mailing lists, or if there has been shipping reputation damage recently, it pays not to send the mail out at once. For example, you can 5.000 emails per hour send, even if your mailing list is smaller than 5,000. Keep your bounce rate below 2%.
Conclusion: Deliverability is more than just technology
Deliverability is not an IT party. It is marketing, reputation management and customer service all in one. By paying attention to data quality, technology and especially interaction, you increase the chances of success in the inbox and beyond.
Keep testing, keep learning and, above all, keep looking critically at your own campaigns. Because if your mail doesn’t arrive, the rest doesn’t really matter anymore. Do you have questions or doubts about something? Get in touch with us!
