Why is my Klaviyo shared IP having Gmail deliverability issues?
Matthew Whittaker
Co-founder & CTO, Suped
Published 9 May 2025
Updated 16 Aug 2025
9 min read
Dealing with a sudden drop in Gmail deliverability for your Klaviyo emails can be incredibly frustrating, especially when other email clients seem unaffected. Many businesses face this challenge, often seeing a significant decline in open rates and revenue, while feeling stuck with generic support responses from their email service provider.
The core of the issue often lies in the complexities of shared IP addresses and how Gmail’s sophisticated filtering algorithms operate. While shared IPs offer benefits for new or lower-volume senders, they also introduce a unique set of risks that can disproportionately impact your sender reputation with major inbox providers like Gmail.
This guide will help clarify why your Klaviyo shared IP might be experiencing specific Gmail deliverability issues. We’ll explore the factors at play, common reasons for performance dips, and provide actionable troubleshooting tips to help you regain inbox placement and protect your email revenue.
Understanding shared IP addresses
When you send emails through an email service provider (ESP) like Klaviyo, you typically use either a shared IP address or a dedicated IP address. A shared IP means your emails are sent from an IP address that is also used by many other Klaviyo customers. This setup is common and offers advantages, especially for senders who don't have the volume or consistent sending patterns required to maintain a dedicated IP’s reputation.
The primary benefit of a shared IP is that the ESP (or their underlying Mail Transfer Agent, MTA) manages the IP reputation. They are responsible for keeping the shared IP in good standing by monitoring the sending practices of all users on that IP. However, the downside is that your sending reputation is tied to the behavior of others. If a few bad actors on the same shared IP start sending spammy content or experience high bounce rates, it can affect everyone on that IP, potentially leading to deliverability issues for your emails, too. You can read more about what a shared IP address is and its impact on email deliverability.
While Klaviyo generally does a good job of managing their shared IP pools to minimize impact from poor senders, issues can still arise. A common scenario is when a shared IP (or the domain associated with it, like a shared return-path domain) gets blocklisted (or blacklisted) due to the actions of a few problematic clients, affecting the deliverability of all others on that shared infrastructure. This can sometimes result in emails going to the spam folder or experiencing delivery delays, especially with certain mailbox providers.
Gmail's focus on domain reputation
Gmail operates with highly sophisticated machine learning filters that are constantly evolving. Unlike some other mailbox providers, Gmail places a much stronger emphasis on domain reputation over IP reputation. This means that even if you're on a shared IP that's experiencing issues, Gmail's system is very good at selectively blocking mail based on your specific sending domain's history and subscriber engagement.
Their algorithms analyze how your recipients interact with your emails, including opens, clicks, replies, and crucially, spam complaints or deletions without opening. If recipient actions indicate that they don’t want or like your mail, Gmail’s reputation engine will likely start placing your messages in the bulk or spam folder, regardless of your shared IP. This explains why you might see problems with Gmail deliverability while other email clients remain stable, as each ISP has its own unique filtering criteria. You can learn more about Google's email sender guidelines.
Another factor that can sometimes be overlooked is the reputation of domains linked within your email content. If you've recently changed a Content Delivery Network (CDN) or hosting service for images, tracking pixels, or other elements within your emails, and that service has a poor reputation, it could negatively impact your Gmail deliverability. Gmail's filters analyze all aspects of your email, including external domains referenced. Even when your IP or domain reputation seems healthy, deliverability can still drop, as explored in articles like Why is Gmail deliverability down despite good reputation.
Gmail's reputation hierarchy
Gmail's primary focus for deliverability is on the sender's domain reputation, which is influenced by factors like engagement, spam complaints, and authentication. While IP reputation matters, it's often secondary to domain health within Gmail's ecosystem. Misconceptions about this are often debunked by email deliverability experts.
Authentication impact
Proper email authentication (SPF, DKIM, DMARC) is critical. Gmail heavily relies on these protocols to verify sender legitimacy. Any misconfiguration or failure in these can cause emails to land in spam. You can find comprehensive guidance on DMARC, SPF, and DKIM.
Common causes for deliverability issues
Even with Klaviyo’s shared IPs, specific issues can lead to deliverability problems, especially with Gmail. The most common culprit is often not the shared IP itself but rather a combination of factors related to your sending practices and audience engagement.
Poor recipient engagement: If your emails consistently have low open rates, low click-through rates, or high delete rates without opening, Gmail's algorithms will interpret this as a lack of interest and may relegate your messages to spam. This is a common reason for emails going to spam.
High spam complaint rates: Even a small percentage of recipients marking your emails as spam can severely damage your sender reputation with Gmail. This is often an indicator that your content isn't relevant or your list acquisition methods need re-evaluation.
Sending to unengaged segments or old lists: Sending to inactive subscribers or outdated lists can lead to low engagement, high bounce rates, and potentially hitting spam traps, all of which negatively impact your domain reputation with Gmail. This can lead to email deliverability issues.
Authentication issues: Even with a shared IP, your domain’s SPF, DKIM, and DMARC records must be correctly configured and aligned. Gmail increasingly enforces these standards, and any misconfiguration can result in messages being flagged as suspicious or spam. Sometimes issues can arise specifically for Google Workspace but not personal Gmail accounts.
It’s important to remember that Google’s machine learning filters are unique. An issue that only affects Gmail, while other providers remain stable, is a strong indicator that the problem lies with your sending practices as perceived by Gmail’s specific algorithms. This includes the reputation of your domain and any linked assets within your emails, such as images hosted on a CDN.
Causes of deliverability issues
Poor engagement metrics: Low open rates, low click rates, or high unsubscribe rates, particularly with Klaviyo emails.
High spam complaints: Recipients marking your emails as junk or spam.
Invalid email addresses: Sending to non-existent email addresses, resulting in hard bounces.
Poor list hygiene: Not regularly cleaning your email lists of inactive subscribers or spam traps.
Clean your email list: Remove unengaged subscribers and bounced addresses. Consider implementing double opt-in.
Segment and personalize: Send targeted content to highly engaged segments to improve overall engagement metrics.
Troubleshooting and solutions
To address specific Gmail deliverability issues when using a Klaviyo shared IP, a multi-faceted approach focusing on your sending practices and domain reputation is essential. Start by thoroughly analyzing your Google Postmaster Tools (GPT) data. Pay close attention to your domain reputation, spam rate, and authentication sections. GPT provides invaluable insights directly from Gmail’s perspective, which is crucial for identifying the root cause of the problem. If your domain reputation is showing 'low' or 'bad,' this is a clear indicator that action is needed. You can find out more about how to improve domain reputation using Google Postmaster Tools.
Next, meticulously review your email authentication records: SPF, DKIM, and DMARC. Ensure they are correctly configured and that your emails are consistently passing authentication checks. Misconfigurations can lead to Gmail marking your emails as unverified or outright spam. If you’re unsure, check your DNS records for alignment and proper setup. Sometimes, Gmail’s specific requirements can lead to deliverability issues for new IP addresses that can extend to shared environments if not managed carefully.
Finally, focus on optimizing your engagement and list hygiene. Remove unengaged subscribers who haven't opened your emails in a significant period. Segment your lists to send more relevant content to active subscribers. Higher engagement signals to Gmail that your emails are desired, improving your sender reputation. While Klaviyo’s shared IPs are designed to protect deliverability, if your sending volume and consistency are high, you might consider the benefits of a dedicated IP for greater control over your reputation.
Actionable steps to improve deliverability
Regularly check Postmaster Tools: Monitor your domain and IP reputation, spam rates, and feedback loops.
Optimize authentication: Ensure your SPF, DKIM, and DMARC records are correctly configured and pass validation.
Clean your list: Segment out unengaged subscribers and remove invalid addresses to improve metrics.
Improve content: Provide valuable and relevant content to encourage opens and clicks.
Views from the trenches
Best practices
Actively monitor your domain reputation in Google Postmaster Tools. This is crucial for understanding how Gmail perceives your sending domain.
Ensure all your email authentication protocols (SPF, DKIM, and DMARC) are correctly implemented and aligned for your sending domain.
Regularly clean your email lists to remove inactive subscribers and those who consistently don't engage with your emails.
Segment your audience and send highly targeted, personalized content to improve engagement metrics, such as open and click-through rates.
Common pitfalls
Assuming deliverability issues are solely due to a shared IP; often, domain reputation and user engagement are more significant factors.
Ignoring low open rates and high spam complaints specific to Gmail, which indicate problems with Gmail's machine learning filters.
Failing to implement or properly configure DMARC, SPF, and DKIM, which are essential for proving sender legitimacy to Gmail.
Continuing to send to unengaged subscribers, which dilutes engagement metrics and can signal poor sending practices.
Expert tips
Gmail primarily evaluates domain reputation, not just IP. Focus on improving your specific domain's health.
Recipient engagement significantly influences Gmail's filtering; if user reactions are negative, emails will go to spam.
Deliverability issues can be specific to one ISP due to their unique machine learning filters, even if other providers are fine.
DKIM replay attacks can occasionally affect domain reputation in Google Postmaster Tools, warranting close monitoring.
Marketer view
Marketer from Email Geeks says they confirmed emails were landing in spam and experienced a 12 percentage point drop in email revenue, indicating a significant performance impact.
2022-02-08 - Email Geeks
Expert view
Expert from Email Geeks says that Gmail primarily focuses on domain reputation rather than IP reputation, and they are adept at selectively blocking mail.
2022-02-08 - Email Geeks
Moving forward with stronger deliverability
Experiencing deliverability issues with Gmail while on a Klaviyo shared IP can be a complex challenge, but it is rarely insurmountable. The key takeaway is that Gmail's sophisticated filtering places a high priority on your domain's reputation and how actively your recipients engage with your emails.
By proactively monitoring your Google Postmaster Tools, ensuring robust email authentication, diligently managing your email list hygiene, and continually optimizing your content for engagement, you can significantly improve your inbox placement. Addressing these core elements will help you navigate the nuances of shared IPs and strengthen your overall email program, ensuring your messages reach their intended audience.
