What are the potential issues with DuckDuckGo entering the email receiving and forwarding business?
Michael Ko
Co-founder & CEO, Suped
Published 15 Jul 2025
Updated 18 Aug 2025
6 min read
DuckDuckGo, primarily known for its privacy-focused search engine, has expanded into the email space with its Email Protection service. This free email forwarding service aims to enhance user privacy by removing various hidden email trackers and allowing the creation of unique, disposable "@duck.com" email addresses. The idea is to shield personal inboxes from tracking and reduce data exposure.
While the privacy benefits for users are clear, this venture introduces a complex layer to the email ecosystem, particularly for senders. The process of receiving, modifying, and then forwarding emails can disrupt established email authentication protocols and lead to significant deliverability challenges. My focus here is on understanding these potential issues from a sender's perspective.
The core concern lies in how these privacy-enhancing modifications interact with standard email security mechanisms like SPF, DKIM, and DMARC. When a third party intervenes in the email flow, even with good intentions, it can inadvertently compromise the signals that mailbox providers rely on to determine email legitimacy, potentially leading to increased spam classifications or even outright rejections.
Technical implications for email authentication
Email authentication protocols were designed to verify the sender's identity and ensure message integrity. SPF checks if the sending server is authorized by the domain owner. DKIM ensures the email content hasn't been tampered with in transit. DMARC builds upon these, providing a framework for domain owners to specify how mailbox providers should handle emails that fail authentication. When an email forwarding service like DuckDuckGo's intercepts and modifies an email, these protocols can be disrupted.
Specifically, the act of stripping trackers can invalidate the DKIM signature, as the message body is altered. If the forwarding server also changes the "Return-Path" address, it can break SPF alignment, leading to an SPF fail. When both SPF and DKIM fail, DMARC will also fail, signaling to the recipient mailbox provider that the email might be spoofed or illegitimate. This is a common issue with email forwarding services, and it's particularly pronounced when content modifications occur.
When emails fail authentication, the sender's domain reputation can suffer. Mailbox providers interpret authentication failures as potential signs of spam or phishing, even if the original sender is legitimate. This can lead to future emails from that sender being routed to the spam folder or outright blocked. Recovering domain reputation from such a low state can be a lengthy and complex process.
Furthermore, if DuckDuckGo's forwarding infrastructure itself receives a high volume of complaints or is used by malicious actors, its IP addresses could end up on various blacklists (or blocklists). This would mean that any legitimate email forwarded through their service could be caught in the crossfire, regardless of the original sender's reputation. Navigating email blocklists is already a significant challenge for senders, and the addition of a third-party forwarder complicates this even further.
The problem
Authentication issues: Email modifications by the forwarding service invalidate SPF and DKIM, causing DMARC failures and raising red flags for mailbox providers.
Sender reputation risk: Repeated authentication failures or association with blocklisted IPs can negatively impact the sender's domain and IP reputation.
The fundamental issue is that legitimate senders have very little control or visibility into how their emails are handled once they enter the DuckDuckGo forwarding system. If a user reports an issue, such as not receiving DuckDuckGo Email Protection emails, the sender has no direct means to troubleshoot the problem. This lack of transparency can make diagnosing and resolving deliverability issues incredibly difficult, leading to missed communications and frustration.
Impact on email marketing and legitimate communications
For email marketers, the rise of privacy-focused forwarding services presents a unique dilemma. On one hand, respecting user privacy is paramount and aligns with best practices. On the other hand, these services can inadvertently undermine the effectiveness of legitimate email campaigns, transactional emails, and other critical communications. The goal of reaching the inbox with important messages becomes significantly harder.
The privacy features of DuckDuckGo's service, such as tracker removal, while beneficial for users, can also obscure valuable insights for senders. Marketers rely on tracking pixels and links to understand engagement, optimize campaigns, and segment audiences. When these are removed or altered, it creates blind spots, making it challenging to gauge the true performance of an email or to identify issues that might be contributing to poor deliverability.
This tension between user privacy and sender visibility is a growing trend in the email industry, with services like DuckDuckGo Email Protection and Apple's Hide My Email becoming more prevalent. Senders must adapt their strategies, focusing on building strong sender reputation and ensuring robust authentication, regardless of the recipient's chosen privacy tools.
Mitigating potential deliverability issues
To mitigate potential issues, senders should prioritize strong email authentication. This includes properly configuring SPF, DKIM, and DMARC records for all sending domains. Monitoring email deliverability issues and DMARC reports is also critical to identify and address any authentication failures or unexpected email routing behavior.
I also recommend maintaining clean mailing lists and engaging in responsible sending practices. This reduces the likelihood of complaints, which can severely damage sender reputation and lead to blocklisting. Even with services like DuckDuckGo in play, a strong foundation of email best practices remains the most effective defense against deliverability problems.
Views from the trenches
Best practices
Maintain perfectly configured SPF, DKIM, and DMARC records for all your sending domains.
Regularly monitor your DMARC reports to detect authentication failures or unexpected forwarding behavior.
Focus on sending valuable, solicited content to highly engaged subscribers to minimize complaints.
Common pitfalls
Ignoring DMARC aggregate reports that show authentication failures due to forwarding services.
Failing to adapt email tracking strategies in response to privacy features like tracker stripping.
Over-relying on traditional engagement metrics when a significant portion of your audience uses privacy protection.
Expert tips
Implement a DMARC policy of p=quarantine or p=reject progressively to enforce authentication.
Consider alternative engagement metrics beyond traditional opens for segments using email protection.
Actively manage your sender reputation by avoiding spam traps and maintaining clean recipient lists.
Marketer view
Marketer from Email Geeks says if DuckDuckGo's email protection moves out of beta, it will likely create many headaches for legitimate email senders and receivers.
2021-07-22 - Email Geeks
Marketer view
Marketer from Email Geeks says that mail forwarders are dysfunctional in a modern email environment, especially concerning authentication.
2021-07-22 - Email Geeks
The path forward for senders
DuckDuckGo's entry into the email forwarding business, while commendable for its privacy objectives, introduces notable challenges for email deliverability. The core issues revolve around the disruption of email authentication protocols like SPF, DKIM, and DMARC, leading to potential deliverability problems and risks to sender reputation.
For senders, adapting means a renewed focus on robust authentication, diligent monitoring, and maintaining clean lists. While user privacy is a priority, ensuring your legitimate emails reach their intended recipients requires a proactive approach to understanding and navigating these evolving email ecosystems.
Gmail and 
Outlook are increasingly strict with authentication, making it challenging for emails routed through a forwarder to reach the inbox consistently. This can lead to a rise in DMARC verification failed errors and reduced deliverability.
DuckDuckGo Email Protection emails, the sender has no direct means to troubleshoot the problem. This lack of transparency can make diagnosing and resolving deliverability issues incredibly difficult, leading to missed communications and frustration.
