Why does Google Postmaster Tools IP reputation decrease on days when newsletters are sent via Mailchimp shared IPs?

Summary

The decline in Google Postmaster Tools IP reputation on newsletter sending days via Mailchimp's shared IPs is a multifaceted issue. Key factors include Mailchimp's engagement-based IP pools where newsletters often go to less-engaged subscribers from different IPs, high sending volumes triggering spam filters, and the influence of other senders' practices on the shared IP. Poor list hygiene leading to bounces and spam complaints, inconsistent sending patterns, and failure to follow IP warming best practices also contribute to the problem. Ultimately, decreased IP reputation often signals that recipients are not engaging with emails or are marking them as spam.

Key findings

  • Engagement-Based IPs: Mailchimp utilizes engagement-based IP pools, potentially sending newsletters to less engaged subscribers on separate IPs.
  • Volume Spikes: High sending volumes, particularly on shared IPs, can trigger spam filters.
  • Shared IP Influence: The sending practices of other users on shared IPs can affect your IP reputation.
  • List Hygiene: Poor list hygiene, including sending to invalid or unengaged addresses, leads to bounces and spam complaints.
  • Sending Patterns: Inconsistent sending patterns and sudden changes in volume raise red flags for email providers.
  • IP Warming: Failure to properly warm up a new IP address can result in deliverability issues.
  • Low Engagement: Low engagement rates and recipients marking emails as spam can negatively impact IP reputation.
  • Recipient Actions: Lack of recipient engagement with the emails causes spam complaints and decreased IP reputation

Key considerations

  • Maintain Consistent Sending: Establish and adhere to a consistent sending schedule to avoid triggering spam filters.
  • Improve List Hygiene: Regularly clean your email list by removing invalid addresses and unengaged subscribers.
  • Segment Your Audience: Segment your audience based on engagement levels to send more targeted and relevant content.
  • Monitor IP Reputation: Regularly monitor your IP reputation using tools like Google Postmaster Tools.
  • Follow IP Warming Best Practices: If transitioning to a dedicated IP, follow recommended IP warming procedures.
  • Enhance Email Content: Create engaging and valuable email content that encourages recipients to interact with your messages.
  • Monitor Engagement: Track subscriber engagement to identify and address issues impacting IP reputation.
  • Consider Dedicated IP: If deliverability issues persist, consider switching to a dedicated IP address to have more control over your sending reputation.

What email marketers say
13Marketer opinions

The IP reputation observed in Google Postmaster Tools can decrease on newsletter sending days via Mailchimp shared IPs due to several interconnected factors. Mailchimp's system uses engagement-based IP pools, so newsletters are often sent from IPs with lower engagement subscribers, which can lower IP reputation. High sending volumes on shared IPs are viewed with suspicion by spam filters, affecting deliverability. Inconsistent sending patterns and less-than-ideal list hygiene compound the problem, as does the sending volume from other users on the shared IP. Consistently sending high volumes to less-engaged subscribers also damages IP reputation.

Key opinions

  • Engagement-Based IPs: Mailchimp uses separate IP pools based on subscriber engagement. Newsletters often go to less engaged users via different IPs.
  • Volume Spikes: High sending volumes trigger spam filters on shared IPs.
  • List Hygiene: Poor list hygiene leads to bounces and spam complaints, hurting IP reputation.
  • Sending Patterns: Inconsistent sending patterns raise red flags for email providers.
  • Shared IP Influence: The sending practices of other users on shared IPs affect your deliverability.
  • Low engagement rates: Newsletters that subscribers do not find useful lead to decreased IP reputation

Key considerations

  • Consistent Sending: Maintain consistent sending patterns to avoid triggering spam filters.
  • List Hygiene Practices: Regularly clean your email list to remove unengaged subscribers.
  • Monitor Engagement: Track subscriber engagement to identify and address issues impacting IP reputation.
  • Warm-up IP: If moving to a dedicated IP, gradually warm it up to establish a positive reputation.
  • Shared IP Limitations: Understand that shared IPs are influenced by other users' sending habits.
  • Email Content: Ensure that emails are useful to subscribers, so that they are not marked as spam
Marketer view

Email marketer from Neil Patel Digital explains that sending large volumes of emails on specific days can negatively impact IP reputation, especially on shared IPs, as it can trigger spam filters. Consistent sending patterns and gradual increases in volume are recommended.

April 2021 - Neil Patel Digital
Marketer view

Marketer from Email Geeks shares that a yellow reputation in Google Postmaster Tools isn't necessarily bad, as it's labeled as 'good'. Also, if Mailchimp uses separate IPs for engaged and unengaged contacts, lower reputation on IPs sending to unengaged contacts is expected.

January 2023 - Email Geeks
Marketer view

Marketer from Email Geeks explains that Mailchimp uses separate IP pools based on subscriber engagement. Highly engaged subscribers are sent emails over 'special' IPs, while other subscribers go out over 'normal' IPs. Large campaigns send a higher proportion of emails over 'normal' IPs, which may have a medium-to-high reputation compared to the 'special' IPs' high reputation.

September 2024 - Email Geeks
Marketer view

Email marketer from HubSpot shares that one reason an IP reputation can decrease is because of low engagement rates. This is because your emails are not useful to the subscribers.

February 2023 - HubSpot
Marketer view

Email marketer from Woodpecker explains that email servers think you're a spammer if you send emails too quickly, as this is not natural behaviour. This affects your IP reputation.

April 2022 - Woodpecker
Marketer view

Email marketer from Mailchimp explains that Mailchimp uses engagement-based sending, so lower engaged users are likely sent through different IPs, and sending high volume to less engaged users on certain days may negatively affect the IP reputation of those IPs.

April 2023 - Mailchimp
Marketer view

Email marketer from StackOverflow states that Mailchimp's shared IP structure may isolate less engaged users onto certain IPs. Your newsletters going to these users on set days is the cause.

September 2023 - StackOverflow
Marketer view

Email marketer from GlockApps shares that Google Postmaster Tools gives insight into your IP reputation. Sending newsletters and seeing a decrease in IP reputation means your users are not engaging with those emails, or they're being marked as spam.

September 2023 - GlockApps
Marketer view

Email marketer from Email on Acid shares that maintaining consistent sending patterns and avoiding large volume spikes is critical to avoid deliverability issues. Sudden changes raise red flags.

June 2023 - Email on Acid
Marketer view

Email marketer from Litmus explains that poor list hygiene (sending to old, unengaged addresses) leads to higher bounce rates and spam complaints, which negatively affect IP reputation. Cleaning lists regularly is essential.

July 2022 - Litmus
Marketer view

Marketer from Email Geeks suggests that if engagement is good, not to stress too hard about IP reputation on a shared IP, as it's largely outside of your control.

June 2022 - Email Geeks
Marketer view

Email marketer from Reddit shares that volume spikes on shared IPs make email providers suspicious. If you suddenly send much more email than normal, spam filters are more likely to trigger. Consistent sending is key.

June 2022 - Reddit
Marketer view

Email marketer from SendGrid explains that on shared IPs, your reputation is influenced by the sending practices of other users. Spikes in sending volume from other users can affect your deliverability and IP reputation.

September 2024 - SendGrid

What the experts say
2Expert opinions

Google Postmaster Tools IP reputation decreases when newsletters are sent via Mailchimp shared IPs due to high sending volumes to less engaged recipients and general spikes in email volume. Consistent high volume to low-engagement recipients damages IP reputation due to low engagement and low-quality contacts. Email volume spikes compared to regular volume, particularly on shared IPs, also negatively impact IP reputation.

Key opinions

  • High volume to less engaged recipients: Consistently sending to less engaged users damages IP reputation.
  • Spikes in Email Volume: Sudden increases in sending volume can harm IP reputation.
  • Shared IP Addresses: Volume spikes are more detrimental on shared IP addresses.

Key considerations

  • Improve Engagement: Focus on increasing engagement rates with your email campaigns.
  • Maintain Consistent Volume: Avoid large spikes in email sending volume by gradually scaling campaigns.
  • Segment Contacts: Segment your email list to target engaged users and remove less engaged ones.
  • Monitor Reputation: Monitor IP reputation via Google Postmaster Tools to detect and address issues promptly.
Expert view

Expert from Spam Resource explains that consistently high sending volumes to less engaged recipients will likely damage the sender's IP reputation. This can be a result of low engagement rates and low-quality contacts.

May 2022 - Spam Resource
Expert view

Expert from Word to the Wise explains that spikes in email volume (when compared to your regular sending volume) can damage your IP reputation, particularly if you're on shared IP addresses.

January 2022 - Word to the Wise

What the documentation says
4Technical articles

Google Postmaster Tools IP reputation decreases on newsletter sending days via Mailchimp shared IPs due to several factors. These factors include spam complaints, sending to invalid email addresses, sudden spikes in email volume, and sending newsletters to unengaged users. Sender reputation is vital for deliverability to Outlook and Hotmail users, and large sending volumes from new or low-reputation IPs are filtered more aggressively. Also, email servers perform reverse DNS lookups on sending IPs, and failures can negatively affect IP reputation. When starting to send from a new IP, IP warming is a must; otherwise, a high volume of emails will be marked as spam.

Key findings

  • Spam Complaints and Invalid Addresses: Spam complaints and sending to invalid addresses harm IP reputation.
  • Volume Spikes: Sudden spikes in email volume negatively impact IP reputation.
  • Unengaged Users: Sending newsletters to unengaged users damages IP reputation.
  • Sender Reputation Importance: Sender reputation is critical for deliverability to Outlook and Hotmail users.
  • Aggressive Filtering: Large sending volumes from new or low-reputation IPs are filtered more aggressively.
  • Reverse DNS Lookups: Failed reverse DNS lookups negatively affect IP reputation.
  • IP Warming Necessity: IP warming is required when starting to send from a new IP.

Key considerations

  • Reduce Spam Complaints: Implement strategies to reduce spam complaints, such as improving email content and targeting.
  • Maintain List Hygiene: Regularly clean your email list to remove invalid email addresses and unengaged users.
  • Control Volume: Avoid sudden spikes in email volume by gradually increasing sending volume.
  • Implement IP Warming: When starting to send from a new IP, follow IP warming best practices.
  • Check DNS Records: Ensure that your sending IPs have valid reverse DNS records.
Technical article

Documentation from Google explains that IP reputation is affected by factors such as spam complaints, sending to invalid email addresses, and sudden spikes in email volume. Sending newsletters to unengaged users can harm IP reputation.

November 2021 - Google
Technical article

Documentation from Microsoft explains that sender reputation is critical for deliverability to Outlook and Hotmail users. Large sending volumes from new or low reputation IPs are filtered more aggressively. Gradual warm-up is necessary.

August 2024 - Microsoft
Technical article

Documentation from RFC explains that email servers perform reverse DNS lookups on sending IPs, failing this lookup can negatively affect your IP reputation.

June 2022 - RFC-Editor
Technical article

Documentation from SparkPost explains that IP warming is a must when starting to send from a new IP. Suddenly sending out a high volume of emails will result in your emails being marked as spam.

October 2021 - SparkPost