How to optimize your email strategy for 2025: Webinar recap
Email deliverability can make or break your 2025 email strategy. In Mailgun’s “Optimizing Your email strategy in 2025” webinar, industry experts share how to stay out of spam folders, implement must-have authentication, and fine-tune your sending practices for maximum inbox success. Scroll to the bottom to watch the webinar recording.
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Email is the digital cornerstone of communications between brands and consumers. Yet in 2025, ensuring emails reach the inbox – not just get sent – is more challenging than ever. Evolving mailbox provider rules and growing user expectations make deliverability complicated but we’re here to break it down with statistics and insights from our 2025 state of email deliverability report.
In a recent Mailgun webinar, deliverability experts Nick Schafer (Senior Manager of Deliverability & Compliance) and Kate Nowrouzi (VP of Deliverability) discussed key strategies for optimizing email programs. Here are the key takeaways from their session, including insights on delivery versus deliverability, common spam triggers, email authentication, and performance monitoring.
Table of contents
Here are the top five causes for spam placement:
The three top authentication protocols:
Four best practices to protect your email infrastructure:
Five tips for email performance:
Delivery vs. deliverability: what’s the difference?
For many senders, the terms "delivery" and "deliverability" seem interchangeable, but understanding their very different meanings is the trick to improving email success. Delivery refers to whether a message is accepted by the receiving mail server, while deliverability measures where that message lands in the inbox.
What is email delivery?
Delivery
refers to whether a mail server accepts your message. A high delivery rate may still not indicate inbox placement. An email can be counted as "delivered" even if it lands in spam.
What is email deliverability?
focuses on inbox placement and engagement. Emails that land in spam fail deliverability despite being delivered technically.
If you’re confused about the difference between delivery and deliverability and why you need to know what sets them apart, you’re not alone. Only about 12% of those surveyed correctly identified the delivery rate as the percentage of emails sent that are accepted to any folder (including the junk folder).
Which of the following accurately describes the delivery rate metric?
“Sometimes senders forget about deliverability, which is the first piece. When the message is delivered it’s handed off to the recipient server to be placed in the inbox. That’s where deliverability comes into play.”
Nick Schafer - Senior Manager of Deliverability & Compliance Sinch Mailgun
To measure deliverability accurately, track user engagement metrics like opens, clicks, and website visits.
Top five reasons emails land in spam
Avoiding the spam folder is one of the most common challenges senders face, but to overcome it, you need to understand why messages end up there. From list hygiene to sender reputation, mailbox providers look at several factors when filtering emails.
Here are the top five causes for spam placement:
Poor list quality: Spam traps and inactive addresses hurt your sender reputation.
High spam complaint rates: Sending unwanted emails leads to complaints and poor engagement.
Lack of authentication: Failing to set up SPF, DKIM, and DMARC protocols raises red flags with mailbox providers.
Low sender reputation: Poor list hygiene and high bounce rates damage your IP and domain reputation, which may lead to blocklisting.
Spammy content or design: Excessive use of ALL CAPS, suspicious links, and bad HTML formatting can trigger spam filters.
Always use confirmed opt-ins and clean your list regularly to minimize risks from spam traps and invalid emails. Learn about double opt-ins and more in our list management best practices post.
Here’s a bonus tip from our experts. The best way to stay out of spam is to know your audience. Not all users are the same, and they don’t need to be treated the same. Use your data and leverage it with personalization and segmentation for better engagement.
Email authentication: SPF, DKIM, and DMARC
Email authentication is the big cheese, the number one way to be sure your messages are trusted by mailbox providers. It verifies that your messages are legitimate and not spoofed, which helps protect both your brand and recipients from phishing attacks. In 2025, authentication will be critical for inbox placement, especially with new requirements from Gmail and Yahoo.
The three top authentication protocols:
SPF (Sender Policy Framework):
Defines which servers can send on your domain’s behalf.
DKIM (DomainKeys Identified Mail):
Adds an encrypted signature to verify your email's origin.
DMARC (Domain-based Message Authentication, Reporting & Conformance):
Directs providers on handling failed authentication and generates reports for senders.
DMARC is an email authentication protocol designed to give email domain owners the ability to protect their domain from unauthorized use, commonly known as email spoofing. It works by works by using DNS records to specify how an email from a domain should be handled if it fails authentication checks through SPF and DKIM.
DMARC was a big topic in email this year and for good reason. While the new sender requirements currently only mandate a DMARC policy of p=none (which is a monitor only policy), that will likely change. And it should.
“The p=reject policy is the most effective policy. You’re telling the ISPs ‘if I fail authentication reject my traffic’. If you are a financial organization and that scam email lands in the spam folder, someone might click and become a victim of a phishing attack."
Kate Nowrouzi - VP of Deliverability
Aside from protecting senders and recipients, Implementing and enforcing DMARC can enhance your credibility and improve inbox placement.
Are you staying out of the spam folder?
The state of email deliverability 2025
Dive deeper into email deliverability with more from our exclusive report. Find out what hundreds of senders around the world are doing to reach the inbox and hear from experts who’ve spent their careers navigating this complex topic. Explore the insights now. No form filling required.
Best security practices for email senders
A secure sending program is the foundation of good delivery and deliverability. By safeguarding your sending infrastructure and maintaining compliance with ISP guidelines, you can prevent unauthorized access and cyber threats. Strong security practices reduce the risk of spam complaints and maintain your reputation.
Four best practices to protect your email infrastructure:
Use double opt-in to verify sign-ups and provide an easy unsubscribe link to reduce complaints.
Secure your domains with 2FA, strong passwords, and regular audits.
Separate mail streams for transactional and marketing emails to prevent cross-contamination of reputation.
Adopt BIMI to boost brand visibility and trust in supported email clients.
Monitoring and improving email performance
Email success is a continuous process that involves tracking data, interpreting feedback from mailbox providers, and making improvements based on performance insights. By regularly analyzing metrics, you can catch and fix issues before they affect your reputation or deliverability.
Five tips for email performance:
Track engagement metrics: Monitor opens, clicks, and complaints.
Monitor sender reputation: Use tools like Google Postmaster and Microsoft SNDS to check your domain/IP reputation.
Run inbox placement tests: Gauge where emails land before large campaigns.
Clean your list: Implement sunset policies to remove inactive subscribers.
Test and optimize: Experiment with subject lines, content, and segmentation to refine performance.
A great place to start monitoring your email program is by getting a baseline email health score. Learn more about the metrics you can monitor and what they can tell you in our health score post.
Delivery vs deliverability FAQ
What is the difference between deliverability and delivery?
Delivery refers to whether an email is accepted by the recipient's mail server. However, this doesn’t guarantee that the email reaches the inbox. Deliverability focuses on where the email lands (inbox vs. spam) and whether users engage with it.
How can I prevent my emails from landing in the spam folder?
Avoid common spam triggers by maintaining good list hygiene, minimizing complaints, and following email best practices. Ensure your content is relevant and your list is free from spam traps or inactive addresses.
Why is email authentication important for deliverability?
Authentication protocols like SPF, DKIM, and DMARC verify your sender identity, preventing phishing and ensuring that mailbox providers trust your emails. Without proper authentication, your messages may be flagged as spam or blocked altogether.
How can I secure my email sending infrastructure?
Use double opt-in for subscribers, provide easy unsubscribe options, enable two-factor authentication (2FA), and perform regular audits of your sending accounts. Separating transactional and marketing emails on different subdomains or IPs can also prevent issues from affecting all your mail streams.
How do I continuously improve my email performance and deliverability?
Regularly monitor engagement metrics like opens, clicks, and spam complaints. Use tools like Google Postmaster and Microsoft SNDS to track your sender reputation. This will set you apart already, we reported that 70% of senders who took our survey aren’t using these tools.
