Summary
Even with a good domain reputation, invite emails often land in spam due to a confluence of factors. These include improper usage of sender email addresses, authentication issues (SPF, DKIM, DMARC), content resembling unsolicited bulk mail or containing spam triggers, low engagement rates, poor IP reputation, repetitive content, links to new/unknown domains, inadequate email list hygiene, sudden spikes in email volume, user-marked spam, and potential misidentification as list bombing attacks. To mitigate these issues, it's crucial to use owned sender addresses, ensure correct authentication, personalize content, implement double opt-in, check IP reputation, randomize content, build trust, clean email lists, ramp up volume gradually, encourage positive user actions, monitor feedback loops, and monitor DMARC reports.
Key findings
- Incorrect Sender Address: Using user's email addresses, especially those with DMARC, or non-owned 'From' addresses leads to filtering.
- Authentication Failures: Missing or misconfigured SPF, DKIM, and DMARC records cause deliverability problems despite domain reputation.
- Content Issues: Content resembling bulk mail, spam triggers, or poor text/image ratio results in emails being marked as spam.
- Engagement Problems: Low engagement rates with invite emails signal to spam filters that these emails are less important.
- IP Reputation Problems: Even with good domain reputation, a poor IP reputation negatively affects deliverability.
- Repetitive Content: Repetitive email content patterns are flagged as spam, especially with invite systems.
- Unfamiliar Domains: Links to new or unknown domains in invite emails can trigger spam filters.
- List Hygiene: Sending invites to invalid or inactive email addresses harms sender reputation.
- Volume Spikes: Sudden increases in email volume can trigger spam filters, especially from new senders.
- User-Marked Spam: User consistently marking emails as junk will train the Microsoft filters to classify those types of email as spam regardless of domain.
- List Bombing False Positives: Invite emails can be mistakenly flagged as part of a list bombing attack.
Key considerations
- Use Correct 'From' Address: Use an email address you own, preferably a subdomain, in the 'From' header.
- Implement Strong Authentication: Properly configure SPF, DKIM, and DMARC for email authentication.
- Optimize Email Content: Personalize content to avoid looking like bulk mail, remove spam triggers, balance text and images, and use full URLs.
- Encourage User Engagement: Implement double opt-in to confirm users' interest.
- Check Sending IP's Reputation: Ensure your sending IP address isn't on any blacklists and has a good reputation.
- Randomize Email Content: Randomize subject lines and body to avoid repetitive patterns.
- Build Trust Over Time: Build trust, especially linking to a new/unknown domain in an email.
- Maintain Clean Email List: Regularly clean your email list by removing invalid accounts.
- Ramp Up Sending Volume Gradually: Gradually increase the volume of invites sent from a new domain.
- Encourage User Actions: Ask users to mark legit emails as 'not junk' so mail servers can learn overtime.
- Monitor Feedback: Monitor feedback loops and promptly respond to complaints.
- Monitor DMARC reports: Monitor DMARC reports for authentication failures.
- Use Compelling Preheaders: Ensure the email preheader makes the email relevant to the user.
What email marketers say
8 marketer opinions
Even with a good domain reputation, invite emails often land in spam due to various factors. These include content resembling unsolicited bulk mail, low engagement rates, content triggers or spammy words, repetitive content, links to new or unknown domains, and sending to invalid email addresses. Maintaining good email deliverability requires personalizing content, implementing double opt-in, checking IP reputation, using compelling preheaders, randomizing content, building trust with email providers, and regularly cleaning the email list.
Key opinions
- Content Matters: Invite emails are often flagged as spam due to content resembling unsolicited bulk mail or containing spam trigger words.
- Engagement is Crucial: Low engagement rates with invite emails can cause spam filters to learn to treat them as less important.
- IP Reputation: Even with a good domain reputation, a poor IP reputation can negatively impact deliverability.
- Repetitive Content: Spam filters identify repetitive content patterns in invite emails, even with a good domain reputation.
- New Domains: Invite emails with links to new or unknown domains can be flagged as suspicious.
- Email List Hygiene: Sending emails to invalid or inactive email addresses can damage sender reputation.
Key considerations
- Personalize Content: Personalize invite emails to avoid looking like generic bulk mail and to make the content more compelling.
- Implement Double Opt-in: Implement double opt-in to confirm users' interest before sending invites, improving engagement.
- Check IP Reputation: Check and maintain a good IP reputation, potentially using dedicated IP addresses for important transactional emails.
- Randomize Content: Randomize subject lines and email body content to avoid repetitive patterns that trigger spam filters.
- Build Trust with Providers: Build trust with email providers over time, especially when linking to new domains.
- Clean Email List: Regularly clean the email list and remove invalid addresses to maintain good deliverability.
- Compelling Preheaders: Use compelling preheaders in emails to improve open rates and prevent emails from landing in spam.
Marketer view
Email marketer from WebmasterWorld Forum shares to check if the invite system is automatically generating similar content for each email. Spam filters might identify repetitive content patterns as spam, even with a good domain reputation. Try randomizing subject lines and email body content.
3 Feb 2022 - WebmasterWorld Forum
Marketer view
Email marketer from Litmus answers that the preheader of the email is important as it can impact open rates and prevent emails from going to spam. A compelling preheader will make the content of the email more relevant to the user.
20 Mar 2022 - Litmus
What the experts say
8 expert opinions
Even with a good domain reputation, invite emails can still end up in spam due to issues with sender address usage, authentication, content, sending frequency, and potential misidentification as list bombing attacks. Avoid using user email addresses in the From: header, ensure proper SPF, DKIM, and DMARC configuration, carefully craft email content to avoid spam triggers, gradually increase sending volume, and monitor feedback loops to address potential list bombing misclassifications.
Key opinions
- Sender Address Misuse: Using recipient or non-owned email addresses in the From: header, particularly those with DMARC, leads to filtering.
- Authentication Issues: Incorrect or missing SPF, DKIM, and DMARC configurations significantly impact deliverability, regardless of domain reputation.
- Content Triggers: Spam trigger words, URL shorteners, and unbalanced image/text ratios in email content can cause filtering.
- Sending Frequency: Sending large volumes of invite emails suddenly, especially from new domains, can raise red flags.
- List Bombing Misidentification: Invite emails can be filtered if mistakenly identified as part of a list bombing attack.
Key considerations
- Use Correct Sender Address: Always use an email address you own (preferably a subdomain) in the From: header.
- Implement Authentication: Ensure SPF, DKIM, and DMARC are correctly configured to authenticate your emails.
- Optimize Content: Avoid spam trigger words, use full URLs, and maintain a balanced text/image ratio in email content.
- Ramp Up Sending Gradually: Gradually increase the volume of invite emails sent, especially when starting with a new domain or IP.
- Monitor Feedback Loops: Monitor feedback loops and promptly address complaints to avoid being misclassified as a list bombing attack.
Expert view
Expert from Email Geeks explains that sending emails with the user's email address, especially if their domain publishes DMARC, is misuse and likely to be filtered.
19 Jan 2022 - Email Geeks
Expert view
Expert from Email Geeks explains the email address in the From: header should be one that you own, ideally a subdomain of your main domain, and using other people’s email addresses there will cause your mail to be filtered.
17 May 2025 - Email Geeks
What the documentation says
5 technical articles
Even with a good domain reputation, invite emails can still end up in spam due to authentication problems (SPF, DKIM, DMARC), user-marked spam, and sudden spikes in email volume. Correctly configuring authentication, monitoring sender reputation, encouraging users to mark emails as 'not junk,' adopting a gradual ramp-up in email volume, and monitoring DMARC reports for authentication failures are crucial for avoiding spam filters.
Key findings
- Authentication is Critical: Missing or incorrectly configured SPF, DKIM, and DMARC can lead to emails landing in spam, even with a good domain reputation.
- User Feedback Matters: Consistent marking of emails as junk by users can cause filters to automatically classify similar emails as spam.
- Email Volume Impacts Reputation: Sudden spikes in email volume, especially from new domains or IP addresses, can trigger spam filters.
- Strict DMARC: A strict DMARC policy can cause deliverability issues if emails aren't fully compliant with SPF and DKIM.
Key considerations
- Ensure Proper Authentication: Thoroughly configure SPF, DKIM, and DMARC to authenticate your emails and prevent spoofing.
- Monitor Sender Reputation: Monitor your sender reputation using tools like Google Postmaster Tools to identify and address any issues.
- Encourage Positive User Actions: Encourage users to mark invite emails as 'not junk' to improve deliverability over time.
- Gradual Volume Increase: Gradually increase the sending volume over time, especially from new domains or IP addresses, to build a positive sender reputation.
- Monitor DMARC Reports: Monitor DMARC reports to identify and resolve any authentication failures promptly.
Technical article
Documentation from RFC explains that a misconfigured SPF record can cause deliverability issues. If the sending server isn't properly authorized in the SPF record, even with a good domain reputation, the emails can be flagged as spam. Ensure the SPF record includes all legitimate sending sources.
2 Jul 2025 - RFC
Technical article
Documentation from Google shares that ensuring proper authentication (SPF, DKIM, DMARC) is crucial. Even with a good reputation, missing or incorrectly configured authentication can lead to emails landing in spam. Also, they advise monitoring your sender reputation via Postmaster Tools to identify any sudden drops.
17 May 2022 - Google
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