Is email volume decreasing due to mailbox provider requirements?

Summary

Experts, marketers, and documentation collectively suggest that email volume is indeed decreasing due to a confluence of factors primarily driven by mailbox provider requirements. Increased spam filtering, stricter authentication protocols (SPF, DKIM), the need for easy unsubscription mechanisms, and adherence to spam rate thresholds are forcing senders to be more cautious. Emphasis is shifting to sending relevant emails to engaged subscribers, leading to smaller, more targeted campaigns. Economic factors like tech industry slowdown and marketing team layoffs, alongside past expansion potentially hitting diminishing returns, also contribute to the trend. Ultimately, maintaining a positive sender reputation and ensuring deliverability are pushing senders to prioritize quality over quantity, impacting overall email volume.

Key findings

  • Authentication & Spam Filtering: Increased spam filtering, stricter authentication requirements (SPF, DKIM), and spam complaint thresholds from providers like Gmail and Microsoft are leading senders to reduce volume.
  • Engagement-Based Sending: Senders are focusing on quality over quantity, sending to engaged subscribers, and reducing mail to unengaged segments to maintain reputation.
  • Regulation Compliance: Adherence to regulations like CAN-SPAM, along with easy unsubscribe options demanded by mailbox providers, forces list refinement and reduced volume.
  • Economic Influences: Tech industry slowdowns, marketing team layoffs, and potential diminishing returns from past marketing expansion are contributing factors.
  • ISP Rate Limiting: ISPs are using rate limiting which impacts senders who exceed limits.
  • Best Practices Shift: Recent changes to bulk email sending best practices has lead to email senders reducing volume to maintain and improve deliverability

Key considerations

  • Implement Strong Authentication: Ensure SPF, DKIM, and DMARC are correctly implemented to meet mailbox provider requirements and prevent spoofing.
  • Manage Email Lists: Regularly clean email lists, removing unengaged subscribers and managing bounce rates to maintain a healthy sender reputation.
  • Prioritize Engagement: Monitor engagement metrics and focus on providing relevant, valuable content to keep subscribers engaged and reduce spam complaints.
  • Comply with Regulations: Adhere to email marketing regulations (CAN-SPAM, GDPR) and provide easy unsubscribe options to comply with mailbox provider policies.
  • Adapt to Change: Stay updated with the latest email sending best practices and mailbox provider policies, adapting strategies as needed.
  • Consent Based Emails: Prioritize sending emails only to recipients who have given consent.

What email marketers say
10Marketer opinions

Email marketers generally agree that mailbox provider requirements are contributing to a decrease in email volume. This is primarily due to increased spam filtering, stricter authentication policies, a focus on sending to engaged subscribers, and adherence to regulations like CAN-SPAM. Senders are prioritizing quality over quantity, cleaning email lists, and being more cautious to maintain deliverability and a positive sender reputation.

Key opinions

  • Spam Filtering: Increased spam filtering by mailbox providers leads to fewer emails being sent as marketers become more cautious.
  • Authentication: New authentication policies are causing senders to reduce email volume.
  • Engagement Focus: Marketers are focusing on sending to engaged subscribers, reducing overall email volume to unengaged segments.
  • Quality Over Quantity: Senders are prioritizing quality and relevance over sending large volumes of emails.
  • Regulations: Compliance with regulations like CAN-SPAM necessitates refined email lists and opt-in practices, impacting email volume.
  • Reputation Impact: High spam complaint and bounce rates damage sender reputation, resulting in lower deliverability and potentially throttled email volume.

Key considerations

  • Authentication Protocols: Ensure proper email authentication (SPF, DKIM, DMARC) to meet mailbox provider requirements.
  • List Management: Regularly clean email lists to remove unengaged subscribers and reduce bounce rates.
  • Engagement Monitoring: Monitor email engagement metrics (opens, clicks) and adjust sending strategies accordingly.
  • Content Relevance: Focus on delivering relevant and valuable content to subscribers to minimize spam complaints.
  • Compliance: Adhere to email marketing regulations like CAN-SPAM and GDPR.
  • Reputation Management: Actively monitor sender reputation and address any deliverability issues promptly.
Marketer view

Email marketer from SuperOffice states that a high spam complaint rate can lower email volume and inbox placement since mailbox providers see these complaints as a signal of poor email practices.

November 2024 - SuperOffice
Marketer view

Email marketer from Constant Contact details that compliance with the CAN-SPAM Act is essential for reaching inboxes. This influences email volume as businesses refine their lists and only send emails to those who have opted in.

July 2021 - Constant Contact
Marketer view

Email marketer from Sendinblue Blog explains that senders are reducing email volume because of the new authentication policies and spam filter updates implemented by different mailbox providers.

May 2021 - Sendinblue Blog
Marketer view

Email marketer from Mailjet Blog shares that the increased scrutiny from mailbox providers may lead to a decrease in overall email volume as senders become more cautious and focus on sending relevant emails to engaged subscribers.

December 2021 - Mailjet Blog
Marketer view

Email marketer from Hubspot shares that one of the key deliverability tips is to keep your contact lists current. Removing unengaged subscribers ensures email volume is directed to recipients most likely to open and click.

November 2023 - HubSpot
Marketer view

Email marketer from Litmus shares that while email volume may not be decreasing for all senders, changes in engagement rates (opens, clicks) due to privacy measures and mailbox provider filtering could lead some marketers to send less to unengaged segments.

December 2023 - Litmus
Marketer view

Email marketer from Neil Patel's Blog shares that increased spam filtering and deliverability challenges faced by marketers might lead to a reduction in the volume of emails sent as businesses become more cautious.

June 2024 - Neil Patel's Blog
Marketer view

Email marketer from Gmass responds that due to the increased regulations and requirements, email senders are reducing the number of emails they send, especially cold emails.

April 2023 - Gmass
Marketer view

Email marketer from EmailToolTester explains that senders are focusing on quality over quantity due to new deliverability rules. Smaller, more targeted campaigns mean fewer emails are being sent overall.

February 2025 - EmailToolTester
Marketer view

Email marketer from Automizy shares that high bounce rates damage your sender reputation and thus email volume, as many mailbox providers will block emails from senders with excessive bounces.

March 2025 - Automizy

What the experts say
5Expert opinions

Experts attribute the potential decrease in email volume to a combination of factors, including stricter mailbox provider requirements, reduced sending to unengaged recipients, and broader economic trends. Publicity around spam complaint thresholds and authentication requirements are pushing senders to be more cautious. Additionally, some suggest that past expansion might have led to diminishing returns, while others believe layoffs in marketing teams are playing a role.

Key opinions

  • Spam Complaint Awareness: Increased awareness of spam complaint thresholds is causing senders to reduce non-consent-based emails.
  • Authentication Impact: Mailbox provider authentication requirements are indirectly influencing email volume.
  • Diminishing Returns: Past expansion in email marketing may have led to diminishing returns, impacting current volumes.
  • Economic Downturn: Tech industry slowdown and marketing team layoffs contribute to reduced email marketing activity.
  • Best Practices: Changes to best practices, including stricter authentication and spam complaint thresholds, are leading to reduced volume for deliverability.

Key considerations

  • Consent-Based Sending: Prioritize sending emails only to recipients who have given explicit consent.
  • Authentication Compliance: Ensure adherence to mailbox provider authentication requirements.
  • Engagement Optimization: Focus on re-engaging inactive subscribers or removing them from lists.
  • Adaptation to Change: Stay informed about and adapt to evolving email marketing best practices and mailbox provider policies.
  • Holistic Approach: Consider both internal factors (marketing team size, budget) and external factors (economic trends, mailbox provider requirements) when planning email marketing strategy.
Expert view

Expert from Email Geeks suspects that there may have been a dialing down of non-consent based email from otherwise legitimate senders, due to the publicity around spam complaint thresholds and consequences.

October 2022 - Email Geeks
Expert view

Expert from SpamResource.com answers that recent changes to bulk email sending best practices have lead to email senders reducing volume to maintain and improve deliverability. These changes include stricter authentication, spam complaint rate thresholds, and easy unsubscription mechanisms.

October 2023 - Spam Resource
Expert view

Expert from Email Geeks thinks that a lot of folks expanded a LOT in the last 18 months and it might be they've hit the point of diminishing returns.

February 2022 - Email Geeks
Expert view

Expert from Word to the Wise shares that mailbox provider requirements related to authentication and engagement are indirectly influencing email volume. Senders are reducing their sending to unengaged recipients to maintain a positive reputation and improve deliverability, thus impacting the total email volume.

October 2021 - Word to the Wise
Expert view

Expert from Email Geeks responds that it's part of the tech slowdown they're seeing and they've laid off half their marketing teams

February 2025 - Email Geeks

What the documentation says
4Technical articles

Email volume is influenced by mailbox provider requirements, including authentication, list unsubscribe, and spam rate thresholds, as highlighted in documentation from Google, Microsoft, RFC, and SparkPost. Authentication protocols like SPF and DKIM are critical, and senders who fail to comply risk having their emails blocked. Rate limiting (throttling) by ISPs also affects email volume, as exceeding these limits leads to deferred or rejected emails. Compliance with these technical requirements is essential for maintaining deliverability and avoiding a reduction in email volume.

Key findings

  • Authentication Requirements: Google and Microsoft require authentication, affecting email volume based on compliance.
  • Unsubscribe Mechanisms: Google's requirements include easy list unsubscribe options, influencing sender practices.
  • Spam Rate Thresholds: Exceeding spam rate thresholds leads to deliverability issues and potential volume reduction.
  • SPF and DKIM Importance: RFC highlights the increasing use of SPF and DKIM, with non-compliance resulting in blocked emails.
  • Rate Limiting: SparkPost describes how ISPs use rate limiting, which affects email volume by deferring or rejecting emails.

Key considerations

  • Implement Authentication: Implement SPF, DKIM, and DMARC to authenticate emails and improve deliverability.
  • Simplify Unsubscribing: Provide easy and accessible unsubscribe options to comply with mailbox provider requirements.
  • Monitor Spam Rates: Monitor and maintain low spam complaint rates to avoid penalties.
  • Comply with Volume Limits: Understand and comply with ISP rate limits to prevent email deferrals or rejections.
  • Stay Updated: Stay informed about the latest email sending best practices and mailbox provider policies.
Technical article

Documentation from Google Workspace Updates explains new requirements for sending emails to Gmail accounts, including authentication, list unsubscribe, and spam rate thresholds, which can impact email volume as senders adjust their practices.

October 2021 - Google Workspace Updates
Technical article

Documentation from SparkPost describes that ISPs (Internet Service Providers) use rate limiting (throttling) to control the volume of email they accept from a particular sender. This affects email volume because if a sender exceeds the limit, their emails are deferred or rejected.

October 2021 - SparkPost
Technical article

Documentation from Microsoft Postmaster outlines best practices for email senders, including authentication and list management, which can lead to senders reducing volume to comply with guidelines and avoid deliverability issues.

November 2024 - Microsoft Postmaster
Technical article

Documentation from RFC explains that SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) are used to authenticate emails and prevent spoofing. Because of this they are increasing in use, which means that senders who do not follow authentication protocols can have their email volume reduced because it gets blocked by mailbox providers.

June 2021 - RFC