What could cause a sudden drop in email open rates on Flodesk?
Michael Ko
Co-founder & CEO, Suped
Published 16 May 2025
Updated 19 Aug 2025
7 min read
Experiencing a sudden and dramatic drop in email open rates on Flodesk can be incredibly frustrating and alarming. One day you're seeing healthy engagement, and the next, your emails seem to vanish into the digital ether, often landing straight in the spam folder. This isn't just a minor fluctuation, it points to a significant deliverability issue that needs immediate attention.
Such a sharp decline indicates that mailbox providers, like Gmail or Yahoo, have started to flag your emails as suspicious. While Flodesk handles much of the underlying infrastructure, several factors can still lead to a compromised sender reputation or trigger spam filters, even with proper authentication in place.
Investigate the problem's scope
The first step in diagnosing a sudden open rate drop is to understand the full extent of the issue. A 40% to 2% drop overnight suggests a systemic problem rather than a minor content tweak. You need to gather as much data as possible from your Flodesk analytics, focusing on more than just open rates.
Look at other key metrics: Are click-through rates also down proportionally? Have bounce rates spiked? Are there any indications of increased spam complaints? These additional data points can help pinpoint whether the issue is deliverability-specific, engagement-related, or a combination. It's also vital to identify if the problem is universal across all mailbox providers or concentrated with a specific one, like Gmail. If it's a specific provider, that narrows down your troubleshooting efforts significantly.
Implementing seed testing as a regular practice is invaluable. Sending your emails to a diverse set of seed addresses allows you to see exactly where your emails are landing, whether it’s the inbox, spam folder, or promotions tab, before you send to your entire list. This proactive approach can help detect issues early.
Key data points to check
Compare metrics: Evaluate click-through rates, bounce rates, and unsubscribe rates alongside open rates to identify correlations.
ISP performance: Determine if the open rate drop is consistent across all internet service providers or isolated to a few, such as Yahoo Mail.
Timing of the drop: Pinpoint the exact date or campaign after which the drop occurred. This can help identify recent changes.
Analyze sender reputation and IP issues
One of the most common, yet often invisible, culprits behind a sudden open rate drop when using an email service provider like Flodesk is a deterioration in the sending IP's reputation. Flodesk, like many ESPs, uses shared IP pools for its customers. If another sender on your shared IP pool suddenly engages in questionable sending practices, it can negatively impact your deliverability, as the entire pool's reputation (and thus your sender reputation) takes a hit. Your domain reputation is key.
This can manifest as your sending IP or even your domain being added to an email blocklist (or blacklist). When your IP or domain is on a blocklist, mailbox providers are far more likely to route your emails directly to spam or reject them outright. While you might have all email authentication in place, a poor IP reputation can still override those positive signals. It's challenging because Flodesk may not proactively notify you of these changes to their shared IP infrastructure.
Although Flodesk may not directly provide IP monitoring tools, you might be able to find the sending IP by inspecting the raw headers of an email that went to spam. If you notice a drastic change in the IP address family from what you typically send from, it's a strong indicator of an IP pool change or issue. You can use a blocklist checker to see if your sending IP or domain is listed.
Signs of a good sending reputation
Consistent deliverability: High inbox placement rates across major ISPs.
Positive engagement: Regular opens, clicks, and low complaint rates.
Sudden drop in opens: Emails bypassing the inbox and going directly to spam.
Blocklist listings: Your sending IP or domain appears on common email blocklists.
Increased bounces: Higher rates of soft or hard bounces, indicating rejection by mail servers.
Content and engagement factors
Even if your sender reputation is generally sound, changes in your email content can significantly impact deliverability. Mailbox providers use sophisticated spam filters that analyze not only who is sending the email but also what the email contains. This includes subject lines, body copy, image-to-text ratio, and the types of links included. A sudden shift to more promotional language, excessive use of all caps, or certain spam trigger words can cause your emails to be flagged.
Another critical factor is recipient engagement. Mailbox providers closely monitor how subscribers interact with your emails. If your emails are consistently ignored, deleted without opening, or worse, marked as spam, it signals to the provider that your content isn't desired. This negative engagement can severely hurt your sender reputation over time, leading to lower inbox placement and, consequently, lower open rates. This is why cleaning your email list is so important.
Ensure your content remains valuable and relevant to your audience. Avoid using too many images without sufficient text, and be mindful of the domain names of any links you include in your emails. If an external domain you link to has a poor reputation, it could also negatively impact your email's deliverability. Consistent, high-quality content encourages positive engagement and helps maintain a healthy sender reputation.
Element
Impact on deliverability
Subject line
Overly promotional language or excessive punctuation can trigger spam filters.
Image-to-text ratio
Too many images with little text can look suspicious to filters.
Links and hostnames
Linking to disreputable domains or using suspicious tracking links can lead to blocklisting.
Spam trigger words
Certain words or phrases are commonly associated with spam and can cause filtering.
Technical and platform considerations
Even if your content is stellar and your IP reputation seems okay, technical configurations can cause sudden drops. Ensure your domain's email authentication records—SPF, DKIM, and DMARC—are correctly set up and haven't inadvertently changed. A misconfiguration, even a small one, can cause emails to fail authentication checks, resulting in immediate rejection or spam placement. While Flodesk guides you through this, it's worth double-checking your DNS records.
For a platform like Flodesk, a sudden drop can sometimes be linked to internal changes on their end, such as switching sending infrastructure or updating their mail routing. While they should communicate such changes, it’s not always the case, and their support might not immediately identify the root cause. This highlights the importance of regular monitoring and the ability to conduct your own diagnostics.
Even with an ESP, understanding your email deliverability beyond basic metrics is crucial. Implement a DMARC policy with reporting to gain visibility into how mailbox providers are authenticating your emails. This will show you exactly which emails are failing SPF or DKIM and provide insights into potential spoofing or configuration issues.
Regularly conduct seed list tests to proactively identify deliverability issues.
Monitor all email metrics, including clicks, bounces, and spam complaints, not just open rates.
Maintain consistent sending patterns to avoid triggering spam filters.
Implement a DMARC policy to gain visibility into email authentication and potential spoofing.
Common pitfalls
Ignoring sudden and significant drops in open rates, hoping they will self-correct.
Relying solely on an ESP's basic analytics without conducting deeper investigations.
Failing to check if sending IPs have changed or are listed on blocklists.
Overlooking subtle changes in email content or linking practices.
Expert tips
Always analyze content elements like hostnames and links, not just the prose of your emails.
Understand that shared IP pools can unpredictably impact your sender reputation.
Proactively check raw email headers for changes in sending IP families.
Focus on maintaining high subscriber engagement to improve long-term deliverability.
Marketer view
Marketer from Email Geeks says: A sudden drop in open rates often points to content or technical issues rather than just sender reputation, though all metrics should be checked across different ISPs.
May 9, 2024 - Email Geeks
Marketer view
Marketer from Email Geeks says: Examining all available analytics, such as clicks and bounces, is crucial for gaining insights into deliverability problems.
May 9, 2024 - Email Geeks
Next steps for your Flodesk emails
A sudden drop in Flodesk open rates, especially a dramatic one, is a clear sign that your emails are not reaching the inbox as intended. This often points to deeper issues than just content, such as a compromised sender reputation or technical misconfigurations.
By systematically investigating your email metrics, checking your IP and domain against blocklists, carefully reviewing your content, and ensuring your technical setup is flawless, you can diagnose the root cause. Proactive monitoring and adherence to best practices for email deliverability are essential to maintaining healthy open rates and ensuring your messages consistently reach their intended audience.
Flodesk can be incredibly frustrating and alarming. One day you're seeing healthy engagement, and the next, your emails seem to vanish into the digital ether, often landing straight in the spam folder. This isn't just a minor fluctuation, it points to a significant deliverability issue that needs immediate attention.
Gmail or Yahoo, have started to flag your emails as suspicious. While Flodesk handles much of the underlying infrastructure, several factors can still lead to a compromised sender reputation or trigger spam filters, even with proper authentication in place.
