Summary
Emails can end up in the spam folder due to a combination of factors, with sender reputation being a primary concern. This reputation is affected by IP and domain reputation, email content, user engagement, and authentication protocols. Google, Microsoft, and other email providers use these signals to filter spam. Ensuring proper email authentication with SPF, DKIM, and DMARC is crucial for verifying that emails are genuinely sent from the domain. Maintaining a clean email list by removing inactive or invalid addresses is essential to avoid spam filters. Poor content, such as using spam trigger words or having a high image-to-text ratio, can also contribute to spam classification. Practices such as warming up your IP address, obtaining explicit consent, segmenting lists, personalizing content, and providing a clear unsubscribe process can improve deliverability. User reports also directly influence filtering decisions.
Key findings
- Reputation is Paramount: Sender reputation (IP and domain) is a dominant factor in email deliverability.
- Authentication is Critical: SPF, DKIM, and DMARC are essential for proving email legitimacy and preventing spoofing.
- Content Matters: Spam trigger words, high image-to-text ratios, and lack of personalization can lead to spam classification.
- List Hygiene is Key: Maintaining a clean and engaged email list reduces bounce rates and improves sender reputation.
- Engagement Influences: User engagement (opens, clicks) signals the value of emails to providers.
- Consent is Necessary: Obtaining explicit consent from subscribers and providing easy unsubscribe options are crucial.
Key considerations
- Monitor Reputation: Consistently monitor your IP and domain reputation.
- Implement Authentication: Ensure SPF, DKIM, and DMARC are correctly set up.
- Clean Lists Regularly: Remove inactive and invalid addresses from your email list frequently.
- Optimize Content: Avoid spam trigger words, balance image/text, and personalize emails.
- Encourage Engagement: Create valuable content and segmented campaigns to increase opens and clicks.
- Provide Easy Unsubscribe: Make it simple for users to unsubscribe to avoid spam complaints.
- IP Warmup: Warm up your IP gradually when starting new campaigns to build a good sending reputation.
- Get Explicit Consent: Only send emails to recipients who have given explicit consent to receive them.
What email marketers say
12 marketer opinions
Emails can land in the spam folder due to various factors related to sender reputation, email content, authentication, list hygiene, and user engagement. Some users reported Really Good Emails landing in their spam folders, while others received them in their inbox, indicating that the issue may not be universal. Key factors influencing deliverability include sender reputation, authentication (SPF, DKIM, DMARC), email list hygiene (cleaning out inactive or invalid addresses), engagement (open and click rates), spam trigger words, and the ratio of images to text. Best practices involve warming up your IP, obtaining consent, segmenting lists, avoiding spam triggers, personalizing content, and providing a clear unsubscribe process.
Key opinions
- Inconsistent Delivery: Some users received Really Good Emails in their spam folder, while others did not, suggesting targeted or variable filtering.
- Sender Reputation: Sender reputation is a critical factor in determining whether emails land in the inbox or spam folder.
- Authentication: Proper email authentication (SPF, DKIM, DMARC) is essential for verifying that emails are genuinely sent from your domain.
- List Hygiene: Maintaining a clean email list by removing inactive or invalid addresses is crucial for avoiding spam filters.
- Content Matters: Spam trigger words and a high image-to-text ratio can increase the likelihood of emails being flagged as spam.
- User Engagement: Low engagement from subscribers (low open and click rates) can negatively impact sender reputation and deliverability.
Key considerations
- Monitor Sender Reputation: Regularly monitor your sender reputation to identify and address any issues that may affect deliverability.
- Implement Authentication: Ensure that your emails are properly authenticated with SPF, DKIM, and DMARC to improve deliverability.
- Clean Email Lists: Regularly clean your email lists to remove inactive or invalid addresses and improve engagement rates.
- Review Email Content: Avoid using spam trigger words and maintain a balanced image-to-text ratio in your emails.
- Improve Engagement: Implement strategies to improve subscriber engagement, such as personalization and relevant content.
- Easy Unsubscribe: Provide a clear and easy unsubscribe process to prevent users from marking your emails as spam.
- IP Warmup: Warm up your IP address gradually when starting a new email campaign to establish a positive sending reputation.
Marketer view
Email marketer from HubSpot explains that email deliverability best practices include obtaining explicit consent from subscribers, using a dedicated IP address, authenticating your email with SPF, DKIM, and DMARC, monitoring your sender reputation, and avoiding spam trigger words.
18 Feb 2023 - HubSpot
Marketer view
Marketer from Email Geeks shares that Really Good Emails landed in the spam folder for one of their accounts, but the main inbox otherwise.
21 Oct 2023 - Email Geeks
What the experts say
2 expert opinions
Spam filtering is influenced by several factors, including IP address and domain reputation, email content, and user engagement. Poor performance in these areas can lead to emails being marked as spam. Email authentication, through SPF, DKIM, and DMARC, is also crucial for verifying that emails are genuinely sent from the domain and reducing the likelihood of being classified as spam.
Key opinions
- Multiple Factors: Spam filtering decisions are based on a combination of factors, not just one single element.
- Reputation is Key: IP address and domain reputation significantly impact email deliverability.
- Authentication Matters: Proper email authentication (SPF, DKIM, DMARC) is critical for deliverability.
- Engagement Impact: User engagement, or lack thereof, plays a role in spam filtering decisions.
Key considerations
- Monitor Reputation: Continuously monitor and maintain a positive IP address and domain reputation.
- Implement Authentication: Ensure proper implementation of SPF, DKIM, and DMARC for email authentication.
- Optimize Content: Create engaging and relevant email content to encourage user interaction.
- Address Performance: Identify and address any areas where performance is poor to improve deliverability.
Expert view
Expert from Word to the Wise responds that email authentication is critical for deliverability, including SPF, DKIM, and DMARC. Implementing these technologies helps mailbox providers verify that emails are genuinely sent from your domain, reducing the likelihood of being marked as spam.
1 May 2024 - Word to the Wise
Expert view
Expert from SpamResource explains that multiple factors influence spam filtering decisions, including the sending IP address reputation, domain reputation, the content of the email, and user engagement (or lack thereof). Poor performance in any of these areas can lead to emails being filtered as spam.
29 Apr 2024 - SpamResource
What the documentation says
4 technical articles
Email providers like Gmail and Microsoft classify emails as spam based on user reports, sender reputation, content characteristics, and authentication issues. Emails may land in the junk folder if the sender is on a block list, the content resembles spam, or the email fails authentication checks (SPF, DKIM, DMARC). SPF records help prevent sender address forgery, improving deliverability. DMARC protects domains from unauthorized use like phishing and spam by allowing domain owners to instruct email receivers on how to handle messages that fail authentication.
Key findings
- Multiple Factors: Email spam classification depends on several factors, including user reports, sender reputation, content, and authentication.
- User Reports Matter: High user spam reports significantly increase the likelihood of emails being filtered as spam.
- Authentication is Crucial: Failure of authentication checks (SPF, DKIM, DMARC) is a major reason for emails being marked as spam.
- SPF Prevents Forgery: SPF records help prevent sender address forgery, improving deliverability and reducing spam classification.
- DMARC Protects Domains: DMARC enables domain owners to protect their domains from phishing and spam by specifying how to handle authentication failures.
Key considerations
- Monitor Reputation: Regularly check and maintain a positive sender reputation to avoid being flagged as spam.
- Implement Authentication: Ensure that SPF, DKIM, and DMARC are properly implemented to authenticate your emails.
- Review Content: Avoid using spam-like content and ensure compliance with email sending best practices.
- Comply with Standards: Adhere to email sending standards and best practices to improve deliverability.
- Check Blocklists: Ensure that your domain and IP address are not on any blocklists.
Technical article
Documentation from Microsoft Support answers that email may be classified as junk due to various reasons, including the sender being on a block list, the content containing spam-like characteristics, the recipient marking the email as junk, or the email failing authentication checks. They advise checking sender reputation and ensuring compliance with email sending best practices.
12 Jan 2022 - Microsoft Support
Technical article
Documentation from RFC Editor describes how SPF records are a means to prevent sender address forgery, which can be used in phishing emails and spam. This assists the email receiver determine if the email is in fact from the sender and is a means to improve email deliverability and reduce spam classification.
16 Dec 2022 - RFC Editor
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