Summary
The overwhelming consensus from email marketing experts, documentation, and community discussions is that blocking emails solely based on the word "unsubscribe" is a poor strategy. It's unreliable, can block legitimate emails, and interferes with automated processes. Effective spam filtering relies on sender reputation, authentication protocols (SPF, DKIM, DMARC), reducing spam complaints through good email marketing practices, utilizing reputable ESPs, monitoring spam complaint rates, implementing feedback loops, creating safe sender lists, and employing comprehensive IP and domain-based blocklists. Building a quality email list through opt-in methods also significantly reduces the need for aggressive filtering. While blocking might stop some unwanted mail, the risk of false positives and the availability of better alternatives make it an undesirable approach.
Key findings
- Unreliable: Keyword blocking is an unreliable method for filtering spam.
- False Positives: Blocking emails with "unsubscribe" can block legitimate emails (false positives).
- Better Alternatives Exist: Sender reputation, authentication, and engagement are more effective for filtering.
- Interferes with Processes: Blocking based on header content (like List-Unsubscribe) can disrupt automated processes.
- Legitimate Mail Missed: Many illegitimate emails do not contain the word "unsubscribe."
Key considerations
- Sender Reputation: Prioritize building and maintaining a good sender reputation.
- Authentication: Implement SPF, DKIM, and DMARC to authenticate your emails.
- Engaged Subscribers: Focus on sending emails to engaged subscribers to reduce spam complaints.
- Easy Unsubscribe: Provide clear and easy unsubscribe options for recipients.
- Quality Email List: Build a high-quality email list through opt-in methods, avoiding purchased lists.
- Monitoring: Monitor spam complaint rates and implement feedback loops.
- Safe Senders List: Create a Safe Senders List to prevent blocking trusted contacts.
- Aggressive Filtering: Avoid aggressive filtering that could block wanted emails.
- Alternative Keywords: Consider blocking alternative phrases to "unsubscribe" but with extreme caution.
- Balance: Weigh the potential benefits of blocking unwanted emails against the risk of blocking legitimate ones.
- Holistic Approach: Take a holistic approach to email filtering, combining various techniques for optimal results.
What email marketers say
10 marketer opinions
The consensus among email marketers and experts is that blocking emails based solely on the presence of the word "unsubscribe" is not a recommended practice. While it might stop some unwanted cold outreach, it also risks blocking legitimate emails, including newsletters and important communications. More effective strategies focus on sender reputation, authentication protocols (SPF, DKIM, DMARC), reducing spam complaints through good email marketing practices (engaged subscribers, clear unsubscribe links, list segmentation), utilizing reputable ESPs with strong spam filters, educating recipients about marking emails as spam, and avoiding aggressive filtering that often catches wanted emails. Building a good email list through opt-in methods and avoiding spam traps are also recommended.
Key opinions
- Blocking Risk: Blocking emails based on the word "unsubscribe" can lead to blocking legitimate emails.
- Ineffective Solution: Keyword-based blocking is not an effective long-term solution for spam filtering.
- Alternative Solutions: Sender reputation, authentication protocols (SPF, DKIM, DMARC), and reducing spam complaints are more effective spam filtering methods.
- List Quality: Building a high-quality, opt-in email list reduces the need for aggressive spam filters.
Key considerations
- False Positives: Aggressive filtering can lead to false positives, blocking desired emails.
- Sender Reputation: Focus on sender reputation and authentication rather than content-based blocking.
- Email Hygiene: Practice good email marketing hygiene, including clear unsubscribe links and list segmentation, to reduce spam complaints.
- Alternative Filtering: Utilize a reputable ESP with strong spam filters rather than relying solely on keyword blocking.
- Holistic Approach: Take a holistic approach to email filtering, combining various techniques for optimal results.
Marketer view
Email marketer from Email Geeks mentions they understand using the hammer approach to email filtering, especially when small organizations are overwhelmed by unwanted emails. They also use similar tactics with a text blocker app to stop political text messages.
2 Aug 2021 - Email Geeks
Marketer view
Email marketer from EmailOctopus Blog recommends against solely relying on keyword-based blocking. They suggest employing a combination of techniques such as using a reputable email service provider (ESP) with strong spam filters, educating recipients on how to mark emails as spam, and implementing proper email authentication protocols.
13 Apr 2022 - EmailOctopus Blog
What the experts say
6 expert opinions
Experts generally advise against blocking emails solely based on the presence of the word "unsubscribe." While it may catch some unwanted emails, it can also block legitimate correspondence. Better filtering requires more complex and costly solutions. Keyword blocking is unreliable, and content filters can inadvertently block desired content. Prioritizing spam scoring offers a more effective alternative.
Key opinions
- Oversimplification: Simple keyword blocking is not an adequate solution for effective email filtering.
- Potential for False Positives: Content filters, including those targeting "unsubscribe," can block legitimate emails.
- Better Alternatives: Spam scoring and more sophisticated filtering techniques offer more reliable alternatives.
- Illegitimate Mail: Many illegitimate emails do not contain the word "unsubscribe."
Key considerations
- Complexity: Good email filtering is a complex and expensive endeavor.
- Alternative Keywords: Consider blocking alternative phrases, such as "to stop receiving," for emails that don't use "unsubscribe."
- Balance: Weigh the potential benefits of blocking some unwanted emails against the risk of blocking legitimate ones.
- Spam Scores: Filter by spam scores to reduce the amount of unwanted email more effectively.
Expert view
Expert from Email Geeks explains that blocking emails containing the word "unsubscribe" might block a tiny bit of real mail but would block a whole bunch of crap.
14 Apr 2025 - Email Geeks
Expert view
Expert from Word to the Wise explains that simple keyword blocking is a poor solution. Good filtering is difficult, expensive and complex.
1 Oct 2022 - Word to the Wise
What the documentation says
5 technical articles
Email deliverability documentation sources consistently advise against blocking emails based solely on the presence of the word "unsubscribe." They advocate for more sophisticated methods like IP and domain reputation blocklists, Safe Senders Lists, feedback loops, and monitoring spam complaint rates. Blocking based on content alone can lead to false positives and interfere with legitimate automated email processes. Allowing users to easily unsubscribe is recommended instead.
Key findings
- False Positives: Blocking based on content can result in blocking legitimate emails (false positives).
- Ineffective Filtering: Simple keyword filtering is less effective than reputation-based blocklists.
- Interference with Processes: Blocking based on header content can disrupt legitimate automated email processes.
- Importance of Unsubscribe: Providing easy unsubscribe options is crucial and recommended.
Key considerations
- IP/Domain Reputation: Use comprehensive blocklists based on IP addresses and domain reputations.
- Safe Senders: Implement a Safe Senders List to prevent trusted sources from being blocked.
- Feedback Loops: Establish feedback loops and monitor spam complaint rates.
- Sophisticated Methods: Utilize more sophisticated filtering techniques than simple keyword blocking.
Technical article
Documentation from Cisco details the ways in which their system filters emails but highlights the importance of allowing users to unsubscribe from marketing emails, rather than blocking them.
12 Jun 2023 - Cisco
Technical article
Documentation from Microsoft details creating a Safe Senders List to ensure messages from trusted sources don't get blocked by aggressive filtering. Does not recommend keyword blocking.
5 Nov 2022 - Microsoft
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