How did GDPR and email volume spikes affect email deliverability trends?
Michael Ko
Co-founder & CEO, Suped
Published 9 May 2025
Updated 19 Aug 2025
6 min read
The introduction of the General Data Protection Regulation (GDPR) in May 2018 marked a pivotal moment for email marketing. It fundamentally reshaped how businesses could collect, process, and store personal data, including email addresses. Simultaneously, many organizations reacted to GDPR by executing large-scale re-permissioning campaigns, leading to significant and often sudden spikes in email volume.
These two events, while distinct, created a complex environment for email deliverability. Understanding their combined influence is crucial for anyone involved in email marketing, as the trends observed during that period continue to inform best practices today.
The GDPR and its initial effects
GDPR's core principle is that individuals have greater control over their personal data. For email marketing, this translated into stricter requirements for obtaining and managing consent. Businesses could no longer simply add contacts to their lists without explicit, unambiguous permission. This shift was intended to foster transparency and trust between senders and recipients.
Pre-GDPR landscape
Consent: Often implied or soft opt-in, allowing for broader list growth.
Data collection: Less stringent rules, sometimes leading to less engaged or invalid contacts.
Email volume: Tendency to send to larger, less segmented lists.
Post-GDPR landscape
Consent: Explicit and verifiable opt-in is required, promoting higher engagement.
Data collection: Focus on quality and transparency, leading to healthier lists.
Email volume: Generally more targeted and segmented sending practices.
The overarching impact of GDPR on email marketing, as discussed in our detailed guide about how GDPR affected email marketing, has been largely positive in the long run. It forced marketers to adopt more responsible data practices, which in turn fostered better sender reputations and higher engagement rates. While initial adjustments were challenging, the landscape became more focused on value-driven communication rather than sheer volume.
The impact of email volume spikes
Independent of GDPR, email volume spikes have always been a critical factor for deliverability. Internet Service Providers (ISPs), like Gmail, Microsoft, and Yahoo, closely monitor sending patterns. A sudden, uncharacteristic increase in email volume from a particular sender can trigger spam filters, regardless of content quality. This is because such spikes are often indicative of malicious activity, like spam or phishing attempts.
This principle is clearly outlined in articles like Mailforge's insights on how email volume impacts deliverability. ISPs view consistent sending behavior as a sign of a legitimate sender. Any deviation, especially a large jump, can be perceived as suspicious. This can lead to emails being throttled, delayed, or outright rejected, impacting your email domain reputation and potentially landing your IP on a blocklist or blacklist.
When deliverability drops significantly despite low spam and bounce rates, it often points to issues with volume fluctuations or content triggering filters, as we discuss in troubleshooting email deliverability drops. Maintaining a steady sending pattern, or gradually increasing volume through IP warming, is a fundamental best practice for managing email volume and fluctuations.
The intersection of GDPR and volume spikes
The period around GDPR's enforcement saw many organizations launch massive re-permissioning campaigns. Fearing non-compliance and potential fines, businesses sent emails to their entire existing databases, even those segments that had been inactive or unengaged for years. The goal was simple: get explicit consent or remove them from the list.
This rush created an unprecedented scenario where many senders experienced simultaneous, self-inflicted volume spikes. The issue was compounded by sending to old lists. Unengaged recipients were more likely to mark these unexpected re-permissioning emails as spam, leading to higher complaint rates. Additionally, old lists often contain a higher percentage of invalid or abandoned email addresses, resulting in increased hard bounces. Both spam complaints and hard bounces are major red flags for ISPs, negatively affecting sender reputation and inbox placement.
The combined effect was a temporary but noticeable dip in email deliverability for many. Even legitimate senders, acting in good faith to comply with a new regulation, found their emails landing in the spam folder or facing deferred delivery. This highlighted the delicate balance between compliance efforts and maintaining a healthy sending reputation.
This particular period served as a vivid example of how increasing email volume can impact IP reputation, especially when paired with suboptimal list quality. It also provided a real-world stress test for the entire email ecosystem.
Navigating the post-GDPR email landscape
In the aftermath, deliverability largely rebounded as senders adjusted their practices and focused on rebuilding lists with explicit consent. The long-term trend has been towards healthier, more engaged email programs. However, the lessons learned from that turbulent period remain highly relevant for current email marketing best practices.
Central to navigating this landscape is a continued emphasis on consent and list quality. GDPR, as explained by GDPR.eu's guide on email, underscores the importance of protecting personal data. This means regularly cleaning your lists, segmenting your audience, and removing inactive subscribers to avoid high bounce rates and spam complaints. It helps prevent your emails from going to spam, which we cover in detail when discussing why emails go to spam.
Maintaining consistent email volume is also key. If you anticipate a large send, it's advisable to warm up your IP address and gradually increase volume over time. Sudden increases are still penalized by ISPs. Moreover, ensuring your email authentication protocols (SPF, DKIM, and DMARC) are correctly configured helps ISPs verify your legitimacy and improves your chances of reaching the inbox. You can learn more about these in our simple guide to DMARC, SPF, and DKIM.
Should you face deliverability challenges after a significant volume send, recovery is possible. Strategies for recovering email deliverability typically involve reducing volume, cleaning lists, engaging inactive subscribers, and closely monitoring your sender reputation.
Views from the trenches
Best practices
Maintain meticulous list hygiene and regularly remove unengaged or invalid contacts.
Implement strong consent mechanisms, preferably double opt-in, for all new subscribers.
Gradually increase email sending volume over time, rather than sudden spikes, especially for new IPs.
Segment your audience and tailor content to ensure high engagement and low complaint rates.
Continuously monitor your sender reputation and deliverability metrics for early detection of issues.
Common pitfalls
Sending to old, unengaged, or unverified email lists, leading to high bounces and spam complaints.
Ignoring email authentication (SPF, DKIM, DMARC) or having misconfigured records.
Drastic and sudden increases in email volume without prior warming, which flags ISPs.
Failing to provide clear and easy unsubscribe options in all email communications.
Not regularly checking blocklists (or blacklists) for your IP or domain status.
Expert tips
Expert from Email Geeks says that deliverability took a hit around the time of GDPR due to a massive increase in email volume and senders using old lists.
Expert from Email Geeks says that email deliverability should improve as senders revert to their typical sending volumes or adjust to new post-GDPR patterns.
Expert from Email Geeks says that email service providers are generally not favorable towards volume spikes, which can negatively impact sender reputation.
Expert from Email Geeks says that after GDPR, some customers reported specific issues with Hotmail deliverability, requiring mediation.
Marketer from Email Geeks says that a common issue is when email marketing tactics confuse recipients, leading to spikes in spam complaints.
Expert view
Expert from Email Geeks says deliverability took a dip around GDPR due to a massive increase in volume and people sending to old lists.
June 2018 - Email Geeks
Expert view
Expert from Email Geeks says that email deliverability should improve as senders go back to their natural or post-GDPR volume.
June 2018 - Email Geeks
Key takeaways for modern email practices
The GDPR and the ensuing email volume spikes demonstrated a crucial lesson: compliance and deliverability are deeply intertwined. While GDPR aimed to protect user privacy, the initial reaction of mass re-permissioning inadvertently caused temporary deliverability challenges due to the sudden increase in email volume and interactions with unengaged lists. The market quickly adapted, reinforcing the importance of genuine consent, regular list hygiene, and consistent sending patterns.
By adhering to these principles, email marketers can not only ensure compliance but also achieve higher inbox placement rates and foster more meaningful relationships with their subscribers, ultimately leading to better campaign performance.
Gmail, 
Microsoft, and 
Yahoo, closely monitor sending patterns. A sudden, uncharacteristic increase in email volume from a particular sender can trigger spam filters, regardless of content quality. This is because such spikes are often indicative of malicious activity, like spam or phishing attempts.
