What happened when Zerobounce spammed email marketers on Twitter?
Matthew Whittaker
Co-founder & CTO, Suped
Published 30 Jun 2025
Updated 19 Aug 2025
7 min read
The email marketing community thrives on trust and best practices. So, when news broke that a prominent email validation service was engaging in widespread unsolicited communication, it sent ripples through the industry. I first heard about it when I received a direct message on Twitter, and quickly realized I wasn't alone. Many of my colleagues in email deliverability, reputation, and marketing also reported receiving similar unsolicited messages.
The irony of an email validation service, designed to help marketers maintain clean lists and avoid spam, allegedly engaging in spamming was stark. It was a concerning development that highlighted the challenges and delicate balance of sender reputation in our industry.
The incident unfolds: A breach of trust
The initial reports began surfacing rapidly. People were publicly sharing screenshots and voicing their bewilderment on Twitter. It quickly became apparent that this wasn't an isolated incident affecting a handful of individuals; it was a widespread campaign. One marketer noted that it looked like 270,000 of their closest colleagues had also been targeted.
What made this situation particularly unusual was the sender. The company in question, ZeroBounce, is widely known for its email validation services, which are intended to help businesses improve their email deliverability by identifying invalid or risky email addresses. Many in the industry, including myself, have had professional dealings with them or knew of their services. The common sentiment was disbelief that a company promoting email hygiene would engage in such a blatant unsolicited outreach.
Some recipients pointed out that the targeting seemed almost aggressive, even reaching competitors. This lack of segmentation and respect for professional boundaries further fueled the negative reaction. The incident quickly became a talking point, raising questions about ethical marketing and the definition of spam within the email ecosystem. I even learned that the company had a past history with snowshoe spamming, although they had supposedly scrubbed their online presence since then.
The paradox of an email validation service sending spam
The primary service offered by ZeroBounce is to help businesses clean their email lists to improve email deliverability and avoid spam folders or being blocklisted. This incident highlighted a critical disconnect between their stated mission and their actions. It emphasized that even companies providing essential email services are not immune to reputation damage if their own practices fall short of industry standards.
This event underscored a fundamental truth in email marketing: sender reputation is paramount. When a company, regardless of its function, engages in unsolicited mass communication, it risks immediate backlash and damage to its credibility. Spam complaints can severely degrade sender reputation, affecting future deliverability to legitimate subscribers.
Understanding the broader implications for email deliverability
The incident serves as a crucial reminder for all email marketers about the fragility of sender reputation and the severe consequences of straying from ethical practices. When an email service provider (ESP) or an email validation service is perceived as engaging in spam, it not only harms their own brand but also impacts the broader perception of the email industry. This makes it harder for legitimate marketers to reach the inbox, as inbox providers may tighten filters in response to increased spam.
A negative reputation, whether for an individual sender or a service provider, can lead to your emails being directed to the spam folder, or even worse, being completely blocked by internet service providers (ISPs) and email service providers (ESPs). This is why practices like understanding what happens when your domain is on an email blacklist are critical. It can take a long time and significant effort to recover your domain reputation once it's damaged.
Maintaining a healthy sender reputation involves consistent adherence to best practices, robust list management, and proactive monitoring. Here are some key takeaways to ensure your email program remains in good standing:
Best practices for maintaining a strong sender reputation
Consent: Always obtain explicit consent before sending emails. This means no purchased lists or scraped addresses.
List hygiene: Regularly clean your lists to remove inactive subscribers, hard bounces, and known spam traps. Even old lists can cause issues, leading to emails going to spam.
Engagement: Send relevant and engaging content to keep subscribers active. High engagement signals positive sender behavior to ISPs.
Monitor feedback loops: Pay attention to spam complaints and opt-outs. High complaint rates are detrimental to your reputation.
Authentication: Implement SPF, DKIM, and DMARC to verify your sending identity and protect your domain from spoofing.
Ultimately, every email marketer and service provider has a responsibility to uphold the integrity of the email channel. Incidents like this Twitter spam campaign, especially from a company in the deliverability space, serve as a stark reminder of the trust placed in us by our subscribers and the industry as a whole. Maintaining that trust should always be a top priority.
Why email validation matters, and why this was a misstep
Email validation services play a crucial role in modern email marketing. They help businesses reduce bounce rates, avoid spam traps, and improve sender reputation by verifying the legitimacy and deliverability of email addresses before campaigns are sent. However, the efficacy of such services relies heavily on the trust users place in them and their commitment to ethical practices.
The incident underscored the importance of choosing partners who truly adhere to the principles of good email hygiene. Sending unsolicited messages, especially at scale, can quickly erode the very trust that such a service is built upon. It puts into question the internal practices and ethical compass of the company involved, prompting marketers to reassess their tools and strategies. This event was a major misstep for a company whose core business is to prevent such issues for their clients.
The problem: Unsolicited outreach
Acquisition: Collecting email addresses from public sources or third-party lists without explicit consent.
Relevance: Sending generic messages to a broad audience, including competitors or individuals who have not expressed interest.
Impact: Risks immediate negative perception, brand damage, and potential blocklisting by ISPs.
The solution: Consent-based marketing
Acquisition: Building lists through opt-ins, double opt-ins, and clear value propositions.
Relevance: Segmenting audiences and tailoring content to their expressed interests and needs.
The message from the community was clear: while email validation is a valuable tool, it does not supersede the fundamental principle of consent. For any sender, neglecting permission and relevance, whether through email or social media, is a direct path to damaging your domain reputation and impacting overall deliverability. It emphasizes that proper email marketing is not just about technical checks but also about ethical conduct and respect for the recipient.
Rebuilding trust: The path forward for any sender
In the aftermath of such an incident, for any company, the path to rebuilding trust involves transparency, apology, and a clear commitment to rectify the situation and prevent future occurrences. It also means doubling down on the fundamentals of email security and deliverability. Implementing strong authentication protocols is essential to signal legitimacy and prevent malicious actors from impersonating your brand.
Crucially, this event serves as a stark reminder that all email marketers, regardless of their niche, must constantly evaluate their practices and the partners they work with. Maintaining a good sender reputation is a continuous effort, requiring vigilance against actions that could compromise trust, whether internal or external.
Robust email authentication protocols like SPF, DKIM, and DMARC are not just technical requirements; they are foundational to building and maintaining sender trust. When properly configured, they help ensure that only authorized senders can use your domain, thereby protecting your brand's integrity and improving your chances of reaching the inbox. Understanding and troubleshooting DMARC reports from Google and Yahoo is essential for ongoing monitoring.
Authentication Protocol
Purpose
Benefit to Deliverability
SPF
Specifies which mail servers are authorized to send email on behalf of your domain.
Helps prevent spoofing and ensures Gmail and Yahoo recognize your legitimate senders.
DKIM
Adds a digital signature to outgoing emails, verifying the sender and ensuring message integrity.
Helps ISPs confirm the email hasn't been tampered with and improves trust, reducing spam scoring.
DMARC
Builds on SPF and DKIM, telling receiving servers how to handle emails that fail authentication and providing reporting.
Provides visibility into email traffic and allows domains to protect against spoofing and phishing more effectively, boosting Outlook deliverability.
Views from the trenches
Best practices
Always prioritize explicit consent for every email address on your list.
Regularly clean your email lists to remove bounces and unengaged subscribers.
Segment your audience to send highly relevant content, improving engagement.
Proactively monitor your sender reputation and DMARC reports for issues.
Common pitfalls
Purchasing email lists, which often contain invalid addresses and spam traps.
Sending mass emails without proper segmentation or personalization.
Ignoring high bounce rates or spam complaints, leading to reputation damage.
Failing to implement or properly configure SPF, DKIM, and DMARC.
Expert tips
A spike in hard bounces or spam complaints often signals a deeper list quality issue.
Sender reputation is built over time with consistent positive sending behavior.
Engaging with recipients across multiple channels, like social, can reinforce trust.
Regularly review your email service provider's compliance policies to stay informed.
Marketer view
Marketer from Email Geeks says they received the spam message and observed that competitors also received it, noting the communication was not targeted or relevant.
2020-01-29 - Email Geeks
Expert view
Expert from Email Geeks says they found evidence of the company's past involvement in snowshoe spamming, indicating a prior history of problematic practices.
2020-01-29 - Email Geeks
Lessons learned for email marketers
The ZeroBounce Twitter spam incident served as a powerful lesson for the entire email marketing community. It vividly demonstrated that even companies dedicated to deliverability must uphold the highest ethical standards in their own outreach. The incident reinforced the critical importance of consent, relevance, and the delicate nature of sender reputation.
For email marketers, this event highlighted the need to be diligent not only in their own practices but also in evaluating the services and partners they choose. A robust email program relies on a foundation of trust and adherence to best practices, ensuring that messages reach intended recipients without compromising valuable sender reputation. It's a reminder that genuine value, not unsolicited outreach, is the key to long-term success in email marketing.
Gmail and 
Yahoo recognize your legitimate senders.
Outlook deliverability.
