Marketo email deliverability: How to set it up and keep emails in the inbox
It's the perfect Marketo email campaign: images are on point, copy barbed with hooks, personalized content, and a clear call-to-action. You hit send, feeling confident in your success. However, when you check the metrics, the number of opens is dismal, and clicks are non-existent. What went wrong?
You can do everything right, but if your emails suffer from poor deliverability, you’ll struggle to succeed. Understanding and optimizing your Marketo instance for email deliverability is crucial—if you’re not landing in the inbox, then how can your efforts in images, copy, and content pay off?
In this guide, we'll cover the Marketo-specific setup work: configuring SPF and DKIM, understanding how Marketo's IP model works, meeting Gmail and Yahoo's bulk sender requirements, and monitoring deliverability once you're sending.
The basics of email deliverability in Marketo
Let’s start with the basics of email deliverability in Marketo. Multiple components contribute to ensuring your emails are delivered, and all are within your control. Here's what we'll cover in this section:
- Managing sender reputation
- Email content and design
- List management and hygiene
Managing sender reputation in Marketo
Sender reputation is a trust score assigned to your email sending domain and IP, used by ISPs (Internet Service Providers) and Email Service Providers (ESPs) to decide whether to accept, reject, or filter your emails. Your organization's sender reputation has a big role to play in deliverability and maintaining a good reputation is critical to your success.
There are several components of sender reputation in Marketo that you can monitor, including:
- Bounce rates
- A high bounce rate indicates poor list management practices. Bounces can be either hard bounces (permanently unresponsive or non-existent email addresses) or soft bounces (resulting from full inboxes or server issues).
- Spam complaints
- Gmail and Yahoo require bulk senders to keep spam complaint rates below 0.3%, and Google recommends aiming under 0.10%. Cross that line and your mail gets rejected or filtered before content quality ever enters the picture.
- Sending practices
- Suddenly sending a large number of emails can be viewed as suspicious, and organizations with larger email lists may engage in IP warming practices (more on that below).
- Authentication
- Ensure you have correctly configured security settings such as SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance).
- Engagement rates
- Monitoring recipient engagement with your emails through opens, clicks, and unsubscribe rates serves as an early warning system for your sender reputation.
We'll get into the details of each of these elements but for now it's important to know that sender reputation is a combination of factors that must be carefully managed.
Email Content and Design Best Practices in Marketo
Creating high-quality, engaging email content is a good way to ensure long-term deliverability. Marketo provides tools that help optimize your email content and design for high deliverability. For example, ensure your emails are mobile-friendly; use Marketo’s email editor to preview and optimize them for different devices. You can also use no-code email creation tools like Knak to take care of mobile and responsive design automatically.
You should also avoid relying too heavily on images in your emails. Image-only emails have many pitfalls and are regularly marked as spam by email service providers. While images can significantly enhance email engagement, it is crucial to maintain a balance in their usage.
List Management and Hygiene in Marketo
Clean email lists are fundamental to high deliverability. Marketo offers features to help you keep lists clean and ensure good email hygiene. A common challenge for email marketers is that over time, email lists become stale—subscribers move on from their roles, email addresses are deactivated, and subscribers sometimes become unengaged. This can lead to high bounce rates, negatively impacting both deliverability and sender reputation.
A key component of email list management is regular list cleaning. Using Marketo’s Smart List functionality, you can segment and filter contacts who have stopped opening emails, are returning hard bounces, or appear otherwise inactive. You can either remove them entirely from the database or sequester them from your main marketing lists. This will help keep engagement high and bounce rates low.
You should also adopt a proactive approach to list management by implementing double opt-in practices, ensuring that only interested subscribers are added. In the era of privacy regulations such as GDPR and CCPA, employing strong compliance mechanisms can help future-proof your email engagement and ensure adherence to legal requirements. For a deeper understanding, Marketo courses can offer structured insights.
Lastly, providing clear unsubscribe options for users is important. While unfortunate, an unsubscribe isn’t necessarily negative; it allows users to self-select based on their interests and helps automatically regulate the cleanliness of your lists. You can help mitigate this by using a preference center that gives users more options for managing their communication preferences with you.
Technical Aspects of Email Deliverability in Marketo
Achieving high email deliverability requires not only great content and thoughtful list management but also a solid technical foundation. The technical aspects of email deliverability in Marketo are crucial for long-term success. Here's what we'll cover:
- Authentication protocols (SPF, DKIM, and DMARC)
- DNS configuration
- What Gmail and Yahoo require
- Shared, dedicated, and Trusted IPs
- IP Warming
Authentication protocols in Marketo
Authentication protocols have been an integral part of email marketing history. Each protocol—SPF, DKIM, and DMARC—plays a slightly different role in email authentication. Together, these protocols enhance the safety of email marketing for consumers and your users by validating that email senders are who they claim to be. Similarly, they protect your brand by preventing bad actors from impersonating you to deceive consumers.
Let's take a deeper look at each protocol and how to set it up in Marketo.
Sender Policy Framework (SPF)
The Sender Policy Framework (SPF) is an email authentication method designed to detect and block email spoofing. It allows domain owners to specify which IP addresses are authorized to send emails on behalf of their domain. IP addresses function like physical addresses in the real world—if an email comes from an unregistered IP address, the ESP will recognize and flag the email as suspicious.
Setting up SPF for Marketo is a single DNS edit: add include:mktomail.com to your domain's existing SPF record. If the domain has no SPF record yet, publish a TXT record along the lines of v=spf1 mx ip4:[your corporate IP] include:mktomail.com ~all. Repeat this for every domain you send from, and follow Adobe's SPF and DKIM setup instructions for the exact record formats.
DomainKeys Identified Mail (DKIM)
DomainKeys Identified Mail (DKIM) is an email authentication method that uses cryptographic signatures to ensure that email content remains unaltered during transit. Think of DKIM as a specialized signature that verifies the integrity of the email contents and the sender. SPF and DKIM are both essential for modern email authentication.
In Marketo, DKIM setup happens in two places. First, publish the DKIM public key that Marketo provides as a TXT record in your DNS. Then activate the sending domain in the Admin section of your Marketo instance, which tells Marketo to sign outgoing email from that domain with a custom DKIM signature. Skip the activation step and your email is addressed from your domain but sent from an IP address associated with a Marketo domain, which is exactly the mismatch that mailbox providers penalize.
Domain-based Message Authentication, Reporting, and Conformance (DMARC)
Domain-based Message Authentication, Reporting, and Conformance (DMARC) builds on the SPF and DKIM protocols by adding a policy that directs ISPs on how to handle emails that fail authentication checks. DMARC enables proactive protection of your domain from phishing and spoofing attacks by offering a mechanism to review suspicious emails. Together, SPF, DKIM, and DMARC constitute the triumvirate of email authentication protocols.
DMARC stopped being optional in February 2024, when Gmail and Yahoo began requiring it for bulk senders. Adoption reflects that shift: 53.8% of senders have implemented DMARC, up from 42.6% in 2023, according to Mailgun’s State of Deliverability report.
Proper DNS Setup for Email Authentication in Marketo
As part of setting up authentication protocols such as SPF, DKIM, and DMARC, you must ensure your DNS is configured correctly. Your DNS (Domain Name System) functions as your listing in the world’s digital phonebooks. Your DNS records contain crucial information about your IP address and your email authentication details.
As part of your setup with Marketo, you will need to collaborate with your IT team to properly configure your DNS. The core of that work is adding the SPF include and DKIM records described above: include:mktomail.com goes into your SPF record, Marketo's DKIM public key is published as a TXT record, and the domain is activated in the Admin section. It's also worth setting up a branded sending domain and a branded tracking-link domain so the links in your emails match the domain you send from instead of a generic Marketo domain.
What Gmail and Yahoo require from Marketo senders
Since February 2024, Gmail and Yahoo hold anyone sending 5,000 or more messages a day to a hard set of requirements: SPF and DKIM authentication with a DMARC policy in place, one-click unsubscribe honored within two days, and a spam complaint rate below 0.3% (Google recommends staying under 0.10%). The rules are published in Google's email sender guidelines and Yahoo's sender requirements, and they apply to your Marketo sends no matter which IP model you are on. For the full compliance breakdown, see our guide to Gmail and Yahoo authentication requirements for Marketo users.
Shared, dedicated, and Trusted IPs in Marketo
Every Marketo account starts on a shared IP address, sending alongside other Marketo customers. A dedicated IP is a paid add-on, and Adobe sets an eligibility floor in its dedicated IP documentation: at least 100,000 emails per month on a stable campaign cadence. Below that volume, or with a seasonal sending pattern, there is not enough consistent mail to keep the IP’s reputation warm, and Adobe advises against it. In between sits Marketo’s Trusted IP shared pool, a vetted shared option for senders who apply and commit to strict sending best practices.
If you do add a dedicated IP, provisioning comes with Adobe deliverability consultants: warm-up coaching, DNS entries to brand the new IP, activation, and a check-in during the ramp. Whether a dedicated IP is the right call in the first place is a bigger question than Marketo; our guide to dedicated IP addresses walks through the decision.
IP warming in Marketo
IP warming is the process of gradually sending small batches of emails to acclimatize ISPs to your sending behavior. During the warming phase, you will gradually increase the volume of emails sent. IP warming helps establish your sender reputation with ISPs as a legitimate email sender.
In Marketo, how much of this you manage yourself depends on your IP model. On the shared pool, warming is already handled; the IP has an established reputation. On a new dedicated IP, Adobe’s consultants coach the ramp as part of provisioning, and their guidance matches what the data shows: consistent monthly volume matters, and dramatic swings in send volume hurt even a well-warmed IP. For the week-by-week ramp schedule and general warming guidance, see our IP warming guide.
Email Deliverability Metrics in Marketo
Monitoring email deliverability in Marketo is crucial for protecting your sender reputation from negative impacts. With Marketo email reports, you can track deliverability metrics and take corrective action before issues arise.
Here's an overview of email deliverability metrics and how they could impact your marketing efforts.
Metric | Definition | Impact |
|---|---|---|
Bounce Rate - Hard Bounces | Occur when an email is sent to an invalid, closed, or non-existent email address. | High hard bounce rates indicate poor list quality and can harm your sender reputation. |
Bounce Rate - Soft Bounces | Temporary issues such as a full inbox or a server problem. | While less critical than hard bounces, consistently high soft bounce rates should be monitored and addressed. |
Open Rates | The percentage of recipients who open your email. | High open rates indicate that your subject lines are effective and your emails are reaching engaged recipients. Low open rates could signal issues with your sender reputation or subject lines. Consistently low open rates might lead ISPs to classify your emails as spam. |
Click-Through Rates (CTR) | The percentage of recipients who click on one or more links within your email. | High CTRs indicate that your email content is engaging and relevant. Low CTRs may suggest that your content isn’t resonating with your audience, potentially affecting future engagement and deliverability. |
Spam Complaint Rates | The percentage of recipients who mark your email as spam. | High spam complaint rates are a significant red flag for ISPs. If too many recipients mark your emails as spam, your sender reputation will suffer, and ISPs may block your emails entirely. |
Unsubscribe Rates | The percentage of recipients who opt-out of your email list after receiving an email. | While unsubscribes are not as harmful as spam complaints, a high unsubscribe rate indicates that your content might not be meeting recipients’ expectations. Consistently high unsubscribe rates can signal engagement issues and negatively impact your sender reputation. |
Delivery Rates | The percentage of emails that were successfully delivered to recipients’ inboxes. This metric excludes bounced emails. | Low delivery rates can indicate issues with list quality or sender reputation. |
Inbox Placement Rate | The percentage of emails that are delivered to the inbox versus the spam or junk folder. | A high inbox placement rate is crucial for engagement. Low rates may indicate problems with your sender reputation or email content. |
Metric | Bounce Rate - Hard Bounces |
|---|---|
Definition | Occur when an email is sent to an invalid, closed, or non-existent email address. |
Impact | High hard bounce rates indicate poor list quality and can harm your sender reputation. |
Metric | Bounce Rate - Soft Bounces |
|---|---|
Definition | Temporary issues such as a full inbox or a server problem. |
Impact | While less critical than hard bounces, consistently high soft bounce rates should be monitored and addressed. |
Metric | Open Rates |
|---|---|
Definition | The percentage of recipients who open your email. |
Impact | High open rates indicate that your subject lines are effective and your emails are reaching engaged recipients. Low open rates could signal issues with your sender reputation or subject lines. Consistently low open rates might lead ISPs to classify your emails as spam. |
Metric | Click-Through Rates (CTR) |
|---|---|
Definition | The percentage of recipients who click on one or more links within your email. |
Impact | High CTRs indicate that your email content is engaging and relevant. Low CTRs may suggest that your content isn’t resonating with your audience, potentially affecting future engagement and deliverability. |
Metric | Spam Complaint Rates |
|---|---|
Definition | The percentage of recipients who mark your email as spam. |
Impact | High spam complaint rates are a significant red flag for ISPs. If too many recipients mark your emails as spam, your sender reputation will suffer, and ISPs may block your emails entirely. |
Metric | Unsubscribe Rates |
|---|---|
Definition | The percentage of recipients who opt-out of your email list after receiving an email. |
Impact | While unsubscribes are not as harmful as spam complaints, a high unsubscribe rate indicates that your content might not be meeting recipients’ expectations. Consistently high unsubscribe rates can signal engagement issues and negatively impact your sender reputation. |
Metric | Delivery Rates |
|---|---|
Definition | The percentage of emails that were successfully delivered to recipients’ inboxes. This metric excludes bounced emails. |
Impact | Low delivery rates can indicate issues with list quality or sender reputation. |
Metric | Inbox Placement Rate |
|---|---|
Definition | The percentage of emails that are delivered to the inbox versus the spam or junk folder. |
Impact | A high inbox placement rate is crucial for engagement. Low rates may indicate problems with your sender reputation or email content. |
Monitoring tools and LaunchPoint
Marketo’s own reports tell you what was accepted, not where it landed. For inbox placement, the LaunchPoint partner ecosystem includes deliverability and inbox placement monitoring tools: seed-list testing that shows whether mail hits the inbox or the spam folder, blocklist and reputation monitoring, and pre-send validation. If deliverability is business-critical for you, or you have moved to a dedicated IP, pairing Marketo with one of these tools gives you the visibility the built-in Email Performance report cannot.
Achieving high deliverability for a better user experience
Achieving high deliverability is clearly beneficial for your marketing efforts, yet it involves more than just having a solid technical foundation. While a solid technical foundation provides a strong base, delivering a quality user experience with each email is key to long-term success. Engaging subscribers with authentic, meaningful content is the best way to ensure sustainable deliverability in Marketo.
User experience begins with well-designed emails. Tools such as Knak enable the creation of professional, fully responsive emails without writing a single line of code. This enables marketers to craft beautiful emails without navigating the complexities of mobile design or mastering Marketo’s email syntax. Consistently great emails, every time.
If something is already going wrong, bounce rates climbing or mail landing in spam, work through our Marketo email troubleshooting guide to isolate the cause symptom by symptom.
If email deliverability in Marketo is top of mind, check out our video demo to see how you could start building emails today.
Frequently Asked Questions
To repair your email sender reputation, start by improving list hygiene—remove inactive or bounced contacts, and avoid purchased lists. Implement authentication protocols like SPF, DKIM, and DMARC, and gradually rebuild trust with ISPs through consistent, engaging emails to your most active subscribers.
A hard bounce happens when an email is sent to a permanently invalid address, like one that doesn’t exist. A soft bounce is a temporary issue, such as a full inbox or a server problem; repeated soft bounces can still impact your sender reputation.
In Marketo, go to the Analytics section and create a new Email Performance Report. Select the emails you want to analyze, set the timeframe, and review metrics like open rates, CTR, bounces, and unsubscribes to evaluate deliverability and engagement.
Start with the symptom, not the setup. Check bounce codes in Marketo’s Email Performance report to separate hard bounces (bad addresses) from soft bounces (temporary failures), review your spam complaint rate against the 0.3% threshold, and verify SPF, DKIM, and DMARC are passing. Our Marketo email troubleshooting guide walks through each failure mode in detail.
Both. Every Marketo account starts on a shared IP address. A dedicated IP is a paid add-on that Adobe recommends only for senders with at least 100,000 emails per month and a stable sending cadence. Marketo also offers a Trusted IP shared pool for senders who apply and follow strict sending best practices.
