Why are email blocks and bounces higher than normal and are bot unsubscribes happening?

Summary

Elevated email blocks and bounces, alongside bot-driven unsubscribes, stem from a confluence of factors including poor list hygiene (invalid addresses, spam traps, outdated contacts), compromised sender reputation (blacklisting, inadequate authentication - SPF, DKIM, DMARC), fluctuations in recipient behavior, and potential spam attacks. Bot-initiated unsubscribes, often triggered by email scanners, can be mitigated through CAPTCHAs or double opt-in. Additionally, excessive sending volumes can trip spam filters. Correct bounce processing is vital for maintaining a positive sender image. Addressing these issues holistically, including ongoing list maintenance, robust authentication protocols, bot mitigation strategies, and careful analysis of bounce codes, is essential for improving deliverability and ensuring secure email communication.

Key findings

  • List Hygiene: Poorly maintained email lists contribute significantly to increased bounces and blocks.
  • Sender Reputation: A negative sender reputation has a direct and severe impact on email deliverability.
  • Bot Activity: Automated bots are actively unsubscribing users and causing other issues.
  • Authentication: Lack of proper authentication results in email deliverability problems.
  • Sending Volume: Excessive sending of emails can be flagged as SPAM by providers.
  • Recent ISP Changes: Recent changes by Yahoo and Gmail may be a cause

Key considerations

  • Regularly Clean Email Lists: Routinely remove invalid, inactive, and problematic email addresses from your sending lists.
  • Implement Strong Authentication: Ensure SPF, DKIM, and DMARC records are correctly configured to authenticate your email sending.
  • Deploy Bot Mitigation Strategies: Utilize CAPTCHAs, double opt-in, and other techniques to prevent automated unsubscribes.
  • Manage Sending Volume: Gradually ramp up sending volume to avoid triggering spam filters.
  • Process Bounces: Implement a system for processing both soft and hard bounces
  • Monitor Subscriber Complaint Rates: Make sure you implement a feedback loop

What email marketers say
12Marketer opinions

The reasons for higher than normal email blocks and bounces include list quality issues (invalid addresses, spam traps, outdated lists), sender reputation problems (being blacklisted, poor authentication), changes in recipient habits, and potential spam attacks. Bot unsubscribes are often caused by email scanners clicking unsubscribe links, and can be mitigated with CAPTCHAs or double opt-in. Sending too many emails can also trigger spam filters, suggesting a gradual ramp-up of send rates. Processing bounce messages correctly is key to maintaining a good sending reputation. Monitoring unsubscribe patterns and implementing a feedback loop can further improve deliverability.

Key opinions

  • List Quality: Poor list quality (invalid addresses, spam traps, outdated lists) is a major contributor to higher bounces and blocks.
  • Sender Reputation: A damaged sender reputation, potentially leading to blacklisting, significantly impacts deliverability.
  • Bot Unsubscribes: Email scanners and bots are triggering unsubscribes, requiring mitigation strategies.
  • Sending Volume: Sending too many emails too quickly can trigger spam filters.
  • Yahoo and Gmail Issues: Recent issues with Yahoo and Gmail may also be contributing to deliverability problems.

Key considerations

  • List Hygiene: Regularly clean and validate your email lists to remove invalid or inactive addresses.
  • Authentication: Ensure proper email authentication (SPF, DKIM, DMARC) to improve sender reputation.
  • Unsubscribe Mitigation: Implement measures like CAPTCHAs or double opt-in to prevent bot unsubscribes.
  • Send Rate Ramp-Up: Gradually increase sending volume to avoid triggering spam filters.
  • Monitor Unsubscribe Patterns: Track unsubscribe patterns to identify and address potential bot activity or other issues.
  • Bounce Processing: Correctly process bounce messages to identify and remove invalid addresses
Marketer view

Email marketer from StackOverflow mentions that one-click unsubscribe can be exploited by bots, as some email clients and security scanners automatically trigger the unsubscribe link for every email. They suggest monitoring unsubscribe patterns and looking for unusual activity, like multiple unsubscribes from the same IP address in a short period.

December 2022 - StackOverflow
Marketer view

Marketer from Email Geeks says that while looking at logs, they are having subscribers go through every message sent to them in the past month and complain on all of them at one time within seconds of each complaint. These subscribers have been on the list for a while and have interacted positively. Suggesting it is a possible complaint bombing by a bot.

November 2024 - Email Geeks
Marketer view

Email marketer from Reddit suggests that bot unsubscribes are a common issue caused by email scanners or bots that automatically click unsubscribe links. The user recommends implementing measures like CAPTCHAs on unsubscribe pages or using double opt-in to prevent bots from unsubscribing users.

June 2021 - Reddit
Marketer view

Email marketer from Neil Patel Digital explains that increased bounces could be due to sending to invalid email addresses, poor list hygiene, or a damaged sender reputation. Also, high bounce rates can lead to deliverability issues.

October 2022 - Neil Patel Digital
Marketer view

Email marketer from SuperOffice says email bounces can be the result of a variety of reasons including; hard bounces, soft bounces and general bounces.

December 2023 - SuperOffice
Marketer view

Email marketer from Automizy explains that a potential cause of bounces is list fatigue. Users are becoming disinterested in the email and are not interacting with it, eventually leading to bounces.

October 2024 - Automizy
Marketer view

Email marketer from DigitalMarketer says a reason that email sends can be blocked is due to being blacklisted by spam filters due to low sender reputation.

July 2024 - DigitalMarketer
Marketer view

Marketer from Email Geeks states that Yahoo and Gmail have been causing issues for many and that ISPs are tightening up security due to cyber warfare, but confirmation won't be given by any major ISP.

August 2022 - Email Geeks
Marketer view

Marketer from Email Geeks asks if Jill is looking at soft or hard bounces, whether the issues are limited to specific mailbox providers or across the board, and suggests searching recent convos about Yahoo and Gmail issues. She also says that if the issues aren't related to Yahoo and Gmail, the issues may be attributed to their own behaviors.

April 2024 - Email Geeks
Marketer view

Email marketer from Mailjet responds that a sudden increase in bounce rate can happen due to an outdated list, change in recipient habits or a spam attack. Mailjet suggests re-confirming your subscribers and checking your IP reputation.

March 2024 - Mailjet
Marketer view

Email marketer from ActiveCampaign explains that sending too many emails within a short period of time can trigger spam filters that assume you are sending unsolicited emails. They suggests slowly ramping up send rate.

February 2022 - ActiveCampaign
Marketer view

Email marketer from Sendinblue explains that a sudden surge in bounces could indicate a problem with list quality, such as an increase in spam traps or inactive addresses. It recommends cleaning the list and authenticating the sending domain.

May 2023 - Sendinblue

What the experts say
2Expert opinions

Correctly processing bounces and mitigating bot traffic are crucial components of email deliverability. Ignoring hard bounces harms sender reputation due to continued sending to invalid addresses. A comprehensive strategy should address both bounce management and the prevention of automated bot activity.

Key opinions

  • Bounce Processing: Incorrectly handling bounces (especially hard bounces) negatively impacts sender reputation and deliverability.
  • Bot Mitigation: Failing to mitigate automated bot traffic in email campaigns will have a negative impact.

Key considerations

  • Implement Bounce Processing: Establish a process for accurately identifying and removing bounced email addresses from sending lists.
  • Mitigate Bot traffic: Implement safeguards to protect against spam bots.
Expert view

Expert from Spam Resource responds that mitigating automated bot traffic needs to be a key part of any email marketing campaign.

July 2024 - Spam Resource
Expert view

Expert from Word to the Wise explains that correctly processing bounces is critical for maintaining a good sending reputation. Ignoring hard bounces results in continued sending to invalid addresses, impacting deliverability. She also recommends implementing a feedback loop to handle complaints effectively.

March 2023 - Word to the Wise

What the documentation says
4Technical articles

Email blocks and bounces can be caused by sender reputation issues, authentication failures (SPF, DKIM, DMARC), high spam complaint rates, sending unsolicited emails, invalid recipient addresses, server problems, content filters, infrastructure and quota issues, and bots and malware. Reviewing bounce codes and following sender guidelines are crucial for troubleshooting and improving deliverability; patching systems helps protect from bots and malware.

Key findings

  • Sender Reputation: Poor sender reputation is a primary cause of email blocks.
  • Authentication: Authentication failures (SPF, DKIM, DMARC) contribute to deliverability problems.
  • Bounce Reasons: Bounces result from various technical and content-related issues.
  • Bot/Malware Impact: Bots and malware can negatively affect email deliverability and data security.

Key considerations

  • Follow Guidelines: Adhere to sender guidelines provided by major email providers (e.g., Google, Microsoft).
  • Analyze Bounce Codes: Carefully analyze bounce codes to identify the root causes of delivery failures.
  • System Security: Keep systems patched and secure to prevent bot/malware activity.
  • Implement Authentication: Implement robust email authentication to improve deliverability.
Technical article

Documentation from RFC 3464 (Bounce Message Format) explains that bounces can result from infrastructure problems, quota issues, invalid addresses, policy reasons and content issues. The recommendation is to read the response codes.

December 2023 - RFC 3464
Technical article

Documentation from Spamhaus explains that bots and malware can cause issues. It is essential to keep your system patched to block bad traffic and ensure that all customer data is safe.

February 2022 - Spamhaus
Technical article

Documentation from Google Postmaster Tools explains that emails might be blocked due to sender reputation, authentication issues (SPF, DKIM, DMARC), high spam complaint rates, or sending unsolicited emails. Google recommends following their sender guidelines to improve deliverability.

April 2023 - Google Postmaster Tools
Technical article

Documentation from Microsoft Support explains that bounces can occur due to various reasons, including invalid recipient addresses, server issues, or content filters. Microsoft recommends reviewing the bounce codes provided in the non-delivery report (NDR) to identify the specific cause.

September 2023 - Microsoft Support