Intro to email deliverability

Email deliverability is the measure of whether your messages are accepted by mailbox providers and placed in the inbox, rather than diverted to spam or blocked outright. It goes beyond simply sending mail through your platform. Deliverability reflects how receiving servers evaluate your domain, IP, and sending practices to decide if the message is trustworthy enough to deliver to the recipient.

The reason deliverability is important is pretty straightforward. The top of your email marketing funnel does not start at sends, it starts at opens. If your email never makes it to the inbox, your funnel has already shrunk before you even begin.

We have all experienced poor deliverability. Your boss asks why messages are landing in spam. Or you notice an unusual number of emails being blocked or bouncing back. Even the best-designed campaigns can become invisible if deliverability is not working in your favor.

The main drivers of deliverability include:

• Reputation: Internet service providers look at engagement and complaints to decide if your messages are trustworthy.

• Authentication: Protocols like SPF, DKIM, and DMARC confirm that you are really the sender.

• List quality: Permission-based, well-managed lists reduce bounces, spam traps, and unsubscribes.

• Content and sending patterns: Relevant, consistent emails are less likely to raise red flags.

Think of deliverability as the foundation of your entire email program. Without it, everything else you do in strategy, design, and copywriting will not reach your audience. Read through our series here:

1. Intro to email deliverability

2. Authentication 101: SPF, DKIM, DMARC explained simply

3. How ISPs judge your emails: reputation, engagement, spam traps, complaints

4. List hygiene and data quality: why clean lists matter more than big lists

5. Content and design factors: subject lines, html, images, links, spam triggers

6. Infrastructure and sending practices: shared vs dedicated IP, warming, throttling

7. Monitoring and troubleshooting: how to use seed tests, blocklist checks, analytics

8. Future of deliverability: AI filters, gmail and yahoo changes, privacy trends

This post is part of our deliverability series. Check out the full guide here.