How many emails do you send per week — a few thousand or a few million? And how many of them actually reach your subscribers? In this article, you can catch ideas that offer a clear roadmap for a smarter, more targeted email strategy.
We recently hosted a webinar on Stripo’s YouTube channel with email deliverability expert Keith Kouzmanoff. We explored the many layers of what actually impacts inbox placement today, looking at outdated myths, modern best practices, and how marketers can build healthier email programs in 2025 and beyond.
During this session, one viewer asked a simple but essential question: “What’s considered a good email deliverability rate?”
Keith didn’t hesitate:
A good delivery rate? 100%. And I’m not joking.
According to him, you can live with 99%, or maybe even 95% or 93%. But it all depends on context. If you’re selling a product or sending travel confirmations with ticketing info, what should your delivery rate be? 100%. There’s no excuse for not hitting that number. If you’re not getting close to 100%, there’s likely something wrong with your data, or your list might not be worth sending in the first place.
In this article, we clarify what “100% deliverability rate” really means (and what it doesn’t), debunk a few persistent myths, and share expert insights, actionable advice, and real-world examples from the webinar. You’ll walk away with a more realistic, technically informed view of deliverability and clear next steps to improve your own performance.
What can happen to your emails, and who controls delivery?
Let’s distinguish between two important stages:
- Delivery — when all emails have been accepted by the receiving server.
- Deliverability — the ability to deliver emails to the inbox, not just the mailbox.
So what can happen between the first and second stages? The moment your email is accepted, several things can happen:
- it may go to the inbox;
- it may go to spam;
- it may be dropped silently;
- it may be throttled;
- it may be delayed.
The receiving system makes these decisions based on complex algorithms that the sender cannot influence in real time. In addition, these algorithms are influenced by the recipients themselves.
The person who owns the inbox, or the organization operating the mailbox, has full control. Email providers determine whether a message is delivered, filtered, or discarded. As a sender, you only control part of the process: what you send, who you send it to, how often, and how your infrastructure is configured.
The key is understanding the distinction between delivery (getting the message to the mailbox provider) and deliverability (getting the message into the right folder — ideally the inbox). These are not the same.
Authentication and domain alignment
Authentication protocols like SPF, DKIM, and DMARC are foundational. They tell the mailbox provider that the email is authorized and hasn’t been tampered with. But authentication alone doesn’t guarantee inbox placement.
Using a consistent domain identity is critical. For example, if your envelope-from, return-path, and friendly-from all come from different domains, that inconsistency may hurt deliverability.
Changing domains frequently or manipulating filters undermines trust. Establishing a stable, authenticated, and clearly aligned identity is more important than trying to “trick” the system.
Content and engagement
Content matters in context. There is no longer a universal “spammy” word list. What triggers a filter for one recipient might not for another. Context and prior behavior drive filtering.
The content you send is significant, but what really matters is how people interact with it. Mailbox providers watch how recipients engage: opens, clicks, replies, deletes, unsubscribes, spam complaints. Low engagement signals that people don’t want your mail.
Keith gave an example of a newsletter that had a 70% open rate from a small, loyal base. Despite low volume, their emails always landed in the inbox because recipients wanted them. Conversely, sending to a large, disengaged list is a red flag.
Reputation and trust
Mailbox providers build a reputation profile based on sending behavior, recipient interaction, and infrastructure quality. Once damaged, a reputation is difficult to repair.
One participant mentioned asking about warmup tools. Keith noted that while warming up a domain is critical, it’s just one piece of the puzzle. Sending slowly and gradually is about giving mailbox providers time to learn who you are.
Don’t just warm up the IP or domain. Warm up the relationship with the receiver. Consistent sending patterns, permission-based lists, and relevant content help build a sender’s reputation over time.
Mistakes senders make
Common errors include:
- using no-reply addresses (which discourage engagement);
- sending with inconsistent sender domains;
- buying or scraping lists;
- sending to unengaged or inactive subscribers;
- ignoring bounce codes and not removing invalid emails addresses;
- assuming that authentication alone guarantees inboxing.
One company was using a vendor that failed to align domain identity. Their DMARC reports showed authentication passed, but messages were still being flagged as suspicious due to inconsistent alignment. Once they aligned envelope-from, header-from, and return-path to a single domain, deliverability improved.
Keith also described clients who refused to stop sending to old or unengaged lists, thinking more volume equals more results. It didn’t.
Filters evolve constantly
The filtering systems used by Gmail, Yahoo, Outlook, and others are dynamic and adjust in real time. They use machine learning models that evaluate sender behavior across billions of messages. Even one bad message can impact future deliverability.
The systems are looking for patterns. If a sender starts sending unusual content, increases volume suddenly, or triggers spam complaints, filters may adapt quickly.
Some filters use hybrid models that mix behavioral signals with traditional rules. Others use collaborative filtering, comparing the sender to similar profiles. These models are proprietary, constantly updated, and not transparent.
Want to see deliverability from unexpected angles? Watch our webinar with Keith Kouzmanoff, a master of unexpected metaphors and analogies that make complex email marketing concepts easy to understand. You’ll learn:
- how email marketing is like celebrating Halloween;
- why the introduction of the spam folder in email clients caused panic;
- whether email filters have the right to decide what information we receive.
Five deliverability tactics for 2025
Improving email deliverability in 2025 requires more than just staying out of the spam folder. It demands a strategic, respectful approach built on trust and relevance. Based on insights from the recent webinar, here are five core principles every email marketer should focus on this year:
1. Start with clean, high-quality data
No deliverability strategy works without good data. A reliable email list remains the foundation of any successful email program. That means continuously cleaning your lists, verifying addresses, and avoiding outdated or purchased data. Accurate, permission-based contacts ensure that messages reach real people who actually want to hear from you, making high delivery rates possible from the start.
2. Create valuable, relevant content
Content is still king, but only if it’s crafted with the audience in mind. Emails should be timely, useful, and aligned with what subscribers actually signed up for. Irrelevant or overly frequent messaging, even from a reputable brand, can harm both engagement and reputation. Consistency in tone, purpose, and value builds trust over time, while poor or generic content quickly leads to unsubscribes or spam complaints.
3. Understand and respect customer behavior
The better you know your audience, the better your emails will perform. Using customer data to inform segmentation, timing, and messaging helps ensure that each email is contextually relevant. Respect for subscribers also means respecting their attention, avoiding over-messaging, honoring frequency preferences, and making it easy to opt out if interest fades. When brands respect their subscribers, those subscribers are more likely to respect the brand in return.
4. Build and maintain real trust at scale
Trust isn’t a checkbox — it’s the underlying force behind good deliverability. It’s built slowly through transparency, consistency, and value. That includes proper list acquisition practices, clear opt-ins, and not abusing the inbox with irrelevant offers. For large-scale senders, maintaining trust means treating each subscriber as an individual, not just another address. At scale, trust becomes the gravel and sand on which the entire email marketing structure rests.
5. Align frequency and tone with brand positioning
Brands need to ensure that their email behavior matches their brand identity. For example, a luxury brand should not be emailing like a discount retailer. Four emails a day from a high-end brand can feel intrusive and cheapen the perception of exclusivity. Instead, the tone, frequency, and design of emails should reflect the values and expectations associated with the brand. Staying consistent with brand positioning not only improves engagement but also prevents long-term erosion of trust.
These five tactics are not quick fixes — they’re long-term strategies grounded in respect for the recipient and a deep understanding of the email ecosystem. Marketers who consistently apply them will be well positioned to achieve high deliverability and lasting customer relationships in 2025 and beyond.
Wrapping up
Constantly working on improving deliverability is just part of the job of an email marketer, requiring constant attention and resources. Keith’s message is clear: If you want good deliverability, respect the recipient. Send mail they expect, want, and find valuable. Focus on clarity, consistency, and trust, not on chasing a mythical 100%.
At Stripo, we do everything to reduce the time and effort you spend on email production. Create high-quality emails quickly and easily, freeing up time for real marketing activities, such as improving email deliverability.