Why is Gmail sending mail to spam folders?

Summary

Gmail's spam filters are influenced by several factors, including sender reputation, authentication methods, content quality, and recipient engagement. A poor sender reputation, often resulting from shared IPs or sending unsolicited emails, is a major cause. Proper email authentication using SPF, DKIM, and DMARC is critical to verify sender identity and prevent spoofing. Content quality also plays a role; using spam trigger words or poor formatting can lead to emails being flagged as spam. Recipient engagement, as measured by open rates, click-through rates, and spam complaints, significantly impacts deliverability. Maintaining a clean and engaged email list helps to reduce spam complaints and improve sender reputation. Furthermore, Google recommends ensuring a valid reverse DNS record, keeping spam rates low (monitored via Postmaster Tools), and avoiding unwanted mail. Monitoring Enhanced Status Codes (ETR) and Non-Delivery Reports (NDR) can also provide insights into delivery problems.

Key findings

  • Sender Reputation: A poor sender reputation, often due to shared IPs or sending unsolicited emails, is a significant factor.
  • Authentication is Crucial: SPF, DKIM, and DMARC are essential for authenticating emails and preventing spoofing; their absence increases spam likelihood.
  • Content Matters: Spam trigger words, poor formatting, and irrelevant content can lead to emails being flagged as spam.
  • Engagement Impacts Deliverability: Low engagement rates, high spam complaints, and sending to inactive subscribers negatively impact deliverability.
  • Monitoring is Key: Regular monitoring of sender reputation via Postmaster Tools and analysis of NDRs/ETRs provides insights into deliverability problems.

Key considerations

  • Implement Authentication Protocols: Ensure SPF, DKIM, and DMARC are correctly configured for your sending domain to authenticate your emails.
  • Maintain List Hygiene: Regularly clean your email list by removing inactive subscribers and managing opt-outs to improve engagement.
  • Optimize Content: Refine email content by avoiding spam trigger words, using proper formatting, and providing relevant information.
  • Monitor Sender Reputation: Use Google Postmaster Tools to monitor your sender reputation, spam rates, and feedback loop metrics.
  • Warm-Up IP Addresses: Gradually warm up new IP addresses by starting with small sending volumes and slowly increasing them over time.
  • Review NDRs/ETRs: Analyze Non-Delivery Reports and Enhanced Status Codes to diagnose and address delivery failures.

What email marketers say
10Marketer opinions

Gmail sends emails to spam due to several factors, primarily related to sender reputation, authentication, content, and engagement. A poor sender reputation, often stemming from shared IP addresses or sending unsolicited emails, is a major cause. Lack of proper email authentication (SPF, DKIM, DMARC) makes it difficult for Gmail to verify the sender's legitimacy, increasing the likelihood of spam filtering. Spam trigger words and poor content quality also contribute. Low engagement rates, high spam complaint rates, and sending to inactive subscribers further damage deliverability. To improve inbox placement, strategies include warming up IP addresses, cleaning email lists, personalizing content, monitoring sender reputation, and following Gmail's best practices.

Key opinions

  • Sender Reputation: A poor sender reputation is a primary driver for emails landing in spam, often due to shared IPs or sending unsolicited mail.
  • Authentication: Lack of proper email authentication (SPF, DKIM, DMARC) makes it difficult for Gmail to verify sender legitimacy.
  • Content: Spam trigger words and low-quality content increase the likelihood of being flagged as spam.
  • Engagement: Low engagement rates (opens/clicks), high spam complaints, and sending to inactive subscribers harm deliverability.

Key considerations

  • IP Warmup: Warm up new IP addresses gradually to establish a positive sending reputation.
  • List Hygiene: Regularly clean your email list to remove inactive subscribers and reduce spam complaints.
  • Personalization: Personalize email content to improve engagement and relevance.
  • Monitoring: Monitor sender reputation, engagement metrics, and spam complaints to identify and address deliverability issues promptly.
  • Authentication Setup: Ensure SPF, DKIM, and DMARC are correctly configured to authenticate your emails.
  • Content Quality: Avoid spam trigger words and focus on providing valuable, relevant content to subscribers.
Marketer view

Email marketer from Email Marketing Forum shares that using a free email address, sending emails from a dynamic IP, or not having proper authentication records can cause emails to go to spam. They advise using a professional email address and configuring SPF, DKIM, and DMARC.

June 2024 - Email Marketing Forum
Marketer view

Email marketer from Mailjet explains that reasons for emails landing in spam include a poor sender reputation, spam trigger words in the content, a high spam complaint rate, and missing or incorrect authentication records.

September 2023 - Mailjet
Marketer view

Email marketer from GlockApps details how factors such as IP reputation, domain reputation, content filters, engagement rates, and spam complaints significantly impact whether emails land in the inbox or spam folder. Regular monitoring and optimization are essential.

September 2024 - GlockApps
Marketer view

Email marketer from Gmass shares that improving Google Workspace deliverability involves warming up your Gmail account, avoiding sending emails with URL shorteners, and ensuring your email content is relevant and engaging. They also advise monitoring your sending limits and following Google's best practices.

November 2024 - Gmass
Marketer view

Email marketer from EasyDMARC explains that email authentication (SPF, DKIM, and DMARC) is crucial for improving email deliverability. Proper authentication helps email receivers verify the authenticity of incoming emails and reduces the likelihood of emails being marked as spam.

November 2022 - EasyDMARC
Marketer view

Email marketer from HubSpot explains that common reasons for emails going to spam include using a shared IP address with a poor reputation, having a low engagement rate (opens and clicks), and sending emails to unengaged contacts. They recommend cleaning your email list and improving email content.

July 2024 - HubSpot
Marketer view

Email marketer from Sendinblue shares that improving email deliverability involves warming up your IP address, segmenting your email list, personalizing your emails, and removing inactive subscribers. They also advise monitoring your sender reputation and avoiding spam traps.

December 2022 - Sendinblue
Marketer view

Email marketer from EmailOctopus explains that improving email deliverability rates involves using a custom tracking domain, cleaning your email list regularly, and testing your emails with different email clients. They also suggest warming up your IP address before sending large volumes of emails.

April 2023 - EmailOctopus
Marketer view

Email marketer from Reddit user spambegone420 shares that using a dedicated IP address, authenticating your domain with SPF and DKIM, and avoiding spam trigger words can help avoid spam filters. They also recommend monitoring your sender reputation.

May 2024 - Reddit
Marketer view

Email marketer from Litmus explains that factors that impact email placement include sender reputation, authentication, engagement, and spam complaints. They recommend monitoring these factors and taking steps to improve them to ensure emails reach the inbox.

March 2024 - Litmus

What the experts say
5Expert opinions

Gmail's spam filtering can affect sent emails, and although some issues might not directly impact email marketing, factors like content, authentication, and list hygiene play a significant role. Using certain phrases or formatting can trigger spam filters. Proper authentication with SPF, DKIM, and DMARC is essential for verifying your identity as a sender. Maintaining a clean and engaged email list helps to avoid spam complaints and protect your sender reputation, thus preventing emails from landing in spam folders.

Key opinions

  • Content Matters: Specific content elements, like phrases and formatting, can cause emails to be marked as spam.
  • Authentication is Key: Proper authentication (SPF, DKIM, DMARC) is vital for proving sender identity and preventing spam flagging.
  • List Hygiene Prevents Spam: A clean, engaged email list reduces spam complaints and maintains sender reputation.

Key considerations

  • Content Review: Review email content to avoid spam-triggering phrases and formatting.
  • Implement Authentication: Ensure that SPF, DKIM, and DMARC are correctly set up for your sending domain.
  • Maintain List Engagement: Regularly clean your email list, removing inactive users and focusing on engaged subscribers.
Expert view

Expert from Email Geeks shares that this is an entirely legitimate issue, just not one that affects email marketing.

September 2023 - Email Geeks
Expert view

Expert from Word to the Wise, Laura Atkins, explains that factors in content, such as excessive use of certain phrases or formatting, can contribute to emails being flagged as spam. Focusing on delivering valuable and relevant content is key to avoiding filters.

September 2024 - Word to the Wise
Expert view

Expert from Word to the Wise, Dennis Dayman, explains that maintaining a clean and engaged email list is critical. Sending to inactive or uninterested subscribers increases the risk of spam complaints and harms your sender reputation, potentially leading to more emails landing in spam folders.

December 2022 - Word to the Wise
Expert view

Expert from Email Geeks explains that the Forbes article misses a giant piece and it’s not incoming mail, it’s your sent mail that is being affected.

July 2022 - Email Geeks
Expert view

Expert from Word to the Wise shares that proper authentication using SPF, DKIM, and DMARC is vital. Without it, your emails are more likely to be marked as spam because mailbox providers can't verify that you are who you claim to be.

March 2022 - Word to the Wise

What the documentation says
5Technical articles

Gmail sends mail to spam when it detects issues with authentication, sender reputation, and content. Implementing SPF, DKIM, and DMARC is crucial for verifying email authenticity and preventing spoofing. Google recommends maintaining a valid reverse DNS record, keeping spam rates low via Postmaster Tools, and avoiding unwanted mail. DMARC allows domain owners to define how receivers should handle emails failing SPF/DKIM checks. Monitoring Enhanced Status Codes (ETR) and Non-Delivery Reports (NDR) from Microsoft can also reveal spam-related delivery issues.

Key findings

  • Authentication is Critical: SPF, DKIM, and DMARC are essential for authenticating email and preventing spoofing.
  • Sender Reputation Matters: Maintaining a good sender reputation, monitored via tools like Google Postmaster Tools, is vital.
  • DMARC Enhances Security: DMARC allows domain owners to specify how emails failing authentication should be handled, preventing phishing.
  • NDRs Provide Insights: Reviewing Enhanced Status Codes (ETR) and Non-Delivery Reports (NDR) can reveal spam-related delivery problems.

Key considerations

  • Implement SPF, DKIM, DMARC: Ensure all three authentication methods are correctly configured for your domain.
  • Monitor Postmaster Tools: Regularly check Google Postmaster Tools to assess sender reputation and spam rates.
  • Review NDRs/ETRs: Analyze Non-Delivery Reports and Enhanced Status Codes to identify and address delivery issues.
  • Maintain Valid DNS: Ensure your sending IP has a valid reverse DNS record.
Technical article

Documentation from Microsoft explains that specific Enhanced Status Codes (ETR) and Non-Delivery Reports (NDR) can indicate spam-related issues. Reviewing these codes helps identify reasons for delivery failures, such as blocked senders or spam filtering.

October 2023 - Microsoft Support
Technical article

Documentation from RFC-Editor details that DomainKeys Identified Mail (DKIM) uses digital signatures to allow a person taking responsibility for a message to sign it, providing message integrity and authentication.

December 2021 - RFC-Editor
Technical article

Documentation from DMARC.org explains that DMARC helps prevent email spoofing and phishing by allowing domain owners to specify how email receivers should handle emails that fail SPF and DKIM checks. It also provides reporting mechanisms for domain owners to monitor their email authentication performance.

January 2024 - DMARC.org
Technical article

Documentation from Google explains that to prevent mail to Gmail users from being blocked or sent to spam, you should authenticate your email with SPF, DKIM, and DMARC. Ensure your sending IP has a valid reverse DNS record, keep spam rates reported in Postmaster Tools low, and avoid sending unwanted mail.

October 2023 - Google Workspace Admin Help
Technical article

Documentation from OpenSPF explains that SPF (Sender Policy Framework) helps prevent email spoofing by allowing domain owners to specify which mail servers are authorized to send emails on behalf of their domain. Email receivers can then check the SPF record to verify the authenticity of incoming emails.

August 2023 - OpenSPF