What is a good email delivery rate without double opt-in and how to improve it?
Matthew Whittaker
Co-founder & CTO, Suped
Published 8 May 2025
Updated 19 Aug 2025
10 min read
Many marketers, myself included, often grapple with the decision of whether to implement double opt-in for email subscribers. While it is widely acknowledged that double opt-in can significantly improve the quality of your email list and subsequently, your inbox placement, some businesses opt for single opt-in to reduce friction in the signup process. This approach can lead to faster list growth, but it also introduces unique challenges for maintaining a high email delivery rate.
When you're not using a double opt-in, your email list might quickly accumulate unengaged users or even invalid addresses. I've seen situations where businesses maintain delivery rates between 94-98% for their automated flows, like welcome or nurture series, even without double opt-in. At first glance, this might seem acceptable, but it's crucial to understand what these numbers truly represent and what hidden risks they might conceal.
This guide will clarify what constitutes a good email delivery rate in a single opt-in environment and, more importantly, how to improve it. We will cover the key metrics to monitor, the potential pitfalls of single opt-in, and actionable strategies to ensure your messages consistently reach the inbox, rather than landing in spam folders or bouncing entirely. It's about more than just getting emails accepted, it's about getting them seen.
What is a good email delivery rate without double opt-in?
Distinguishing between email delivery rate and email deliverability is a common point of confusion, and it's vital for accurate assessment. The email delivery rate refers to the percentage of emails that are successfully accepted by recipient mail servers. If a server accepts your email, it counts toward this rate. However, this metric doesn't tell you whether the email actually landed in the inbox, the spam folder, or was blocked entirely later on.
On the other hand, email deliverability encompasses the entire journey, measuring how many emails actually reach the recipient's inbox. This is the metric that truly impacts the effectiveness of your email campaigns. A high delivery rate (also known as acceptance rate) is the first hurdle, but ensuring good deliverability is the ultimate goal.
So, what is a good email delivery rate (acceptance rate) without double opt-in? While aiming for 100% is ideal, a range between 98% and 99% is generally considered excellent for businesses not using double opt-in. If your rates drop below 98%, especially approaching 94% or lower, it indicates that a significant number of your emails are being rejected at the server level, which is a clear warning sign. This threshold is often higher than what might be acceptable with a more rigorously managed double opt-in list. You can explore more about what constitutes a good overall email deliverability rate.
Understanding the risks of single opt-in
Operating without double opt-in can indeed pose greater risks to your email program. The primary concern is the higher likelihood of collecting invalid or low-quality email addresses. These can lead to increased bounce rates, particularly hard bounces from non-existent addresses. Frequent hard bounces signal to internet service providers (ISPs) that your list quality is poor, which can negatively impact your sender reputation and lead to more emails being sent to spam or outright blocked.
Another significant risk is a higher spam complaint rate. Without a verification step, it's easier for users to sign up unintentionally or for malicious actors to submit addresses that don't belong to them. When recipients mark your emails as spam, it's one of the strongest negative signals to ISPs, drastically hurting your email reputation. Most experts recommend keeping your spam complaint rate below 0.1%. For detailed benchmarks, you can consult Attentive's guide to email deliverability.
I've personally observed that even if an email is initially accepted by the recipient's server, if it consistently receives spam complaints, Gmail will often start routing future messages to the bulk folder (spam folder), even if the user manually moves them out. This can lead to a deceptive sense of security from high delivery rates while actual inbox placement suffers. Regularly monitoring your Google Postmaster Tools is essential for gaining visibility into these critical metrics, as they provide insights into complaint rates, IP and domain reputation, and delivery errors.
Risks of single opt-in
Lower list quality: More invalid or inactive email addresses on your list.
Higher bounce rates: Increased hard and soft bounces, signaling poor list hygiene to ISPs.
Increased spam complaints: Subscribers may mark unsolicited emails as spam, damaging your reputation.
Reduced engagement: Lower open and click-through rates due to disengaged or fake subscribers.
Key strategies to improve your email delivery rate
Even without double opt-in, you can maintain a robust email program by prioritizing key deliverability best practices. The cornerstone of a healthy email list is rigorous list hygiene. I recommend implementing an email validation API at the point of sign-up, which can catch invalid or risky addresses before they even make it onto your list. This proactive step is crucial for preventing bounces and avoiding spam traps. Remember, the goal is to send emails only to engaged recipients.
Beyond initial validation, regular list cleaning is non-negotiable. I advise setting up automated filters to remove subscribers who consistently soft bounce (e.g., three times in 30 days) or hard bounce immediately. Even more critical is identifying and removing unengaged users, as low engagement can harm your sender reputation just as much as bounces. ISPs track engagement metrics, and sending to inactive subscribers can signal that your content isn't relevant or desired, leading to poorer inbox placement across the board.
Sender authentication is another pillar of good deliverability. Ensuring your Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and DMARC records are correctly configured is paramount. These protocols verify that your emails are legitimate and prevent spoofing, building trust with mailbox providers like Gmail and Microsoft. A strong sender reputation is your best defense against being blacklisted (or blocklisted) and ensures your messages reach their intended destination.
Proactive steps for ongoing deliverability
To effectively improve your email delivery rate without relying on double opt-in, it's crucial to focus on proactive list management and robust email authentication. These two areas are foundational to building and maintaining a positive sender reputation with major mailbox providers.
Single opt-in without mitigation
Higher bounce rates: Due to invalid or abandoned sign-ups.
Increased spam complaints: Higher chance of users marking emails as spam.
Degraded sender reputation: Leading to lower inbox placement and potential blocklists (blacklists).
Single opt-in with best practices
Real-time email validation: Use a service to verify addresses at signup.
Aggressive bounce management: Remove addresses after a few soft or any hard bounces.
Strong authentication: Ensure SPF, DKIM, DMARC are properly configured.
Email authentication protocols are critical for proving your legitimacy as a sender. SPF (Sender Policy Framework) allows you to specify which mail servers are authorized to send email on behalf of your domain. DKIM (DomainKeys Identified Mail) provides a way to digitally sign your emails, ensuring they haven't been tampered with in transit. DMARC (Domain-based Message Authentication, Reporting, and Conformance) builds on SPF and DKIM, giving you control over what happens to emails that fail authentication and providing reports on these failures.
Implementing a DMARC policy, even a permissive one like p=none, is a fundamental step. This allows you to receive DMARC reports, which are invaluable for identifying authentication issues and understanding how different mailbox providers are handling your mail. For more details on this, I recommend checking out Mailgun's guide to improving email deliverability. Proper configuration of these records is a strong signal to ISPs that you are a legitimate sender and helps prevent your emails from being flagged as spam or blocklisted (blacklisted). It’s a foundational element for anyone seeking to improve email deliverability.
In addition to technical setup, it is crucial to monitor your sender reputation proactively. This involves routinely checking your domain and IP addresses against common email blocklists (or blacklists). Being listed can severely impact your delivery rates. Many tools offer blocklist monitoring services that alert you if your sending infrastructure gets listed. Quick detection and remediation are key to minimizing damage and recovering your reputation. Consistent sending practices, relevant content, and careful list management are the best long-term strategies for avoiding these lists.
Sustaining high deliverability
To ensure your email delivery rates remain high and your emails consistently land in the inbox, continuous monitoring and adaptation are essential. I regularly check my Google Postmaster Tools for any shifts in domain reputation or complaint rates. Even small increases in spam complaints can be a red flag, indicating that your list quality or content might be slipping. You can also monitor email open rates as a strong indicator of engagement.
Regularly review your email content and sending practices. Are your subject lines enticing without being misleading? Is your content valuable and relevant to your subscribers? Are you segmenting your audience and sending targeted messages? These factors, while not directly impacting the initial delivery rate, heavily influence whether your emails are opened and engaged with, which in turn affects your long-term deliverability and domain reputation.
Finally, stay informed about changes in mailbox provider policies. Gmail and Yahoo's new sender requirements, for instance, emphasize authenticated sending and low spam complaint rates. Adapting to these changes proactively will help ensure your messages continue to reach their intended recipients, even without the added layer of security that double opt-in provides. Continually refining your strategy is the most effective way to sustain high deliverability rates over time.
Views from the trenches
Best practices
Implement email validation at signup to catch invalid addresses immediately, reducing bounces.
Regularly clean your email list by removing unengaged subscribers and persistent soft bounces.
Ensure SPF, DKIM, and DMARC authentication are correctly configured to build sender trust.
Monitor Google Postmaster Tools and DMARC reports for insights into your reputation and delivery errors.
Prioritize sending valuable and relevant content to encourage engagement and minimize spam complaints.
Common pitfalls
Neglecting email list hygiene, leading to high bounce rates and spam trap hits.
Not configuring SPF, DKIM, and DMARC, which negatively impacts sender authentication.
Sending to disengaged subscribers, which lowers overall engagement metrics and hurts reputation.
Relying solely on delivery rates without also tracking inbox placement and complaint rates.
Expert tips
Even without double opt-in, a 98%+ email acceptance rate indicates a relatively clean list, but monitor inbox placement closely.
For B2B streams without feedback loops (FBLs), reputation degradation from unaddressed complaints can be a silent killer.
Google Postmaster Tools provide valuable complaint rate data, crucial for assessing Gmail deliverability.
If volumes are low, slight fluctuations in delivery rates can be statistical noise, but they still warrant attention as volume scales.
Temporary delivery errors from ISPs often indicate suspected spam; detailed error messages can pinpoint the issue.
Expert view
Expert from Email Geeks says a 94-98% delivery rate is normal for a relatively clean list, but this only represents acceptance at the server, not inbox placement.
November 5, 2024 - Email Geeks
Expert view
Expert from Email Geeks says to keep a close eye on engagement metrics and spam-related bounces, as these are better indicators of email deliverability.
November 5, 2024 - Email Geeks
The path to better inbox placement
Achieving and maintaining a good email delivery rate without double opt-in is entirely possible, but it demands a proactive and meticulous approach to email marketing. While double opt-in offers a built-in layer of protection for list quality, its absence means you must be extra vigilant about every aspect of your sending practices. Focus on the quality of your list, rather than just its size.
By prioritizing robust email authentication, diligent list hygiene, and continuous monitoring of your sender reputation and engagement metrics, you can confidently navigate the complexities of email deliverability. Remember, the goal is not just to have your emails accepted, but to consistently land them in the inbox where they can truly engage your audience and drive results for your business.
Gmail and 
Microsoft. A strong sender reputation is your best defense against being blacklisted (or blocklisted) and ensures your messages reach their intended destination.
