Summary
Emails from Gmail SMTP often end up in Outlook, Hotmail, and Live spam folders due to a complex interplay of factors. These include: Gmail SMTP being perceived negatively, poor IP reputation (influenced by shared IPs and other users' spam), improper authentication (SPF, DKIM, DMARC), spam-triggering content, low engagement, blacklisting, sending to unengaged addresses, failure to warm up the IP, misconfigured DMARC, exceeding Gmail's sending limits, violating Outlook.com's filtering policies, and treating transactional emails as bulk. Microsoft is a particularly challenging recipient with stringent filtering practices.
Key findings
- Reputation Issues: Poor IP reputation due to shared IPs or other users' spam activities on Gmail SMTP leads to flagging by Microsoft.
- Authentication Failure: Improper SPF, DKIM, and DMARC configuration causes deliverability problems with Outlook, Hotmail and Live.
- Content Triggers: Spam filters are triggered by suspicious keywords, phrases, and misleading subject lines within emails.
- Engagement Deficit: Low engagement rates (opens, clicks) trigger spam filters and lead to poor sender reputation.
- Microsoft Stringency: Microsoft has strict filtering policies and may flag emails even with proper authentication.
- Bulk Email Classification: Transactional emails treated as bulk face higher filtering risks.
- Limits Exceeded: Exceeding Gmail's sending limits can trigger spam filters.
- List Hygiene Neglect: Sending emails to old or unengaged email addresses damages the sender's reputation.
- Configuration Issues: Incorrectly configured sending infrastructure further complicates deliverability.
Key considerations
- Authentication Setup: Properly configure SPF, DKIM, and DMARC for email authentication.
- Content Review: Review and optimize email content to avoid triggering spam filters.
- List Hygiene: Regularly clean email lists by removing unengaged subscribers.
- Engagement Improvement: Focus on improving email engagement rates through personalization and relevant content.
- Reputation Monitoring: Monitor IP and domain reputation, addressing blacklist issues.
- Sending Limits Management: Adhere to Gmail's sending limits to avoid throttling.
- Warm-up Strategy: Implement a warm-up strategy for new IPs by gradually increasing sending volume.
- Provider Assessment: Consider using a dedicated SMTP provider with a solid reputation as an alternative.
- Feedback Loop Implementation: Implement feedback loops to monitor spam complaints.
What email marketers say
10 marketer opinions
Emails sent from Gmail SMTP may end up in Outlook, Hotmail, and Live spam folders due to a combination of factors. These include Microsoft's potential dislike of Gmail SMTP, poor IP reputation (potentially influenced by shared IPs used by Gmail and the actions of other users), improper email authentication (SPF, DKIM, DMARC), spam-triggering content, low engagement rates, blacklisting, sending to unengaged email addresses, failure to warm up a new IP address, and misconfigured DMARC policies.
Key opinions
- Microsoft Bias: Microsoft might filter emails more aggressively from Gmail SMTP.
- IP Reputation: A poor IP reputation, potentially due to shared IPs, can lead to emails being flagged as spam.
- Authentication: Lack of proper SPF, DKIM, and DMARC authentication increases the likelihood of emails being marked as spam.
- Content: Suspicious keywords, phrases, or deceptive subject lines can trigger spam filters.
- Engagement: Low engagement rates (opens, clicks) can negatively impact sender reputation and lead to spam filtering.
- Blacklisting: Being blacklisted due to spam complaints can cause emails to be automatically sent to the spam folder.
- List Hygiene: Sending emails to unengaged or old addresses hurts sender reputation.
- Warm-up: Failing to warm up a new IP address or sending too many emails too quickly can trigger spam filters.
- DMARC: Misconfigured DMARC policies can lead to legitimate emails being rejected or sent to spam.
Key considerations
- Email Authentication: Ensure SPF, DKIM, and DMARC are properly configured to authenticate your emails.
- Content Optimization: Review email content and subject lines to avoid spam-triggering words and phrases.
- List Management: Regularly clean your email list to remove unengaged subscribers.
- Engagement Strategies: Implement strategies to improve email engagement rates, such as personalized content and relevant offers.
- IP Reputation Monitoring: Monitor your IP and domain reputation for blacklisting and take steps to address any issues.
- Warm-up Schedule: Gradually increase sending volume over time to establish a positive sender reputation.
- DMARC Configuration: Carefully configure your DMARC policy to balance security and deliverability.
- Evaluate SMTP Provider: Consider switching to a dedicated SMTP provider with a good reputation if Gmail SMTP is consistently causing deliverability issues.
Marketer view
Email marketer from Gmass explains that sending emails to old or unengaged email addresses will hurt sender reputation. Regularly cleaning the email list to remove disengaged contacts improves deliverability to Outlook, Hotmail and Live.
11 Feb 2023 - Gmass
Marketer view
Email marketer from Mailjet explains that spam filters analyze email content for suspicious keywords and phrases. Using high-pressure sales language or deceptive subject lines can trigger these filters, causing emails sent from Gmail SMTP to land in spam folders of Outlook, Hotmail, and Live users.
12 Feb 2024 - Mailjet
What the experts say
5 expert opinions
Emails sent from Gmail SMTP might end up in spam folders in Outlook, Hotmail, and Live due to several expert-identified reasons. Transactional emails are often treated as bulk, increasing the chance of filtering. Issues with the Hubspot-Gmail integration could be contributing. Microsoft's stringent filtering practices, influenced by content, list quality, and sender reputation, can override proper authentication. Furthermore, a myriad of underlying issues, from IP reputation to content, can result in emails being blocked by Microsoft, requiring in-depth analysis. Authentication problems (SPF, DKIM, DMARC) and incorrect infrastructure setup also contribute heavily to deliverability failures.
Key opinions
- Transactional Mail: Transactional emails are often categorized as bulk, affecting deliverability.
- Hubspot-Gmail Integration: The integration between Hubspot and Gmail could be a contributing factor to deliverability problems.
- Microsoft's Stringent Filtering: Microsoft employs rigorous filtering based on content, list quality, and sender reputation, potentially overriding authentication.
- Multitude of Potential Issues: Numerous factors can cause Microsoft to block emails, necessitating a thorough investigation.
- Authentication Configuration: Incorrectly configured authentication (SPF, DKIM, DMARC) and infrastructure are common sources of deliverability problems.
Key considerations
- Evaluate SMTP Provider: Consider alternative SMTP providers to avoid potential issues with Gmail's infrastructure.
- Analyze Email Content: Ensure email content is not triggering spam filters based on keywords or formatting.
- Verify Authentication: Double-check the setup and validation of SPF, DKIM, and DMARC records to guarantee proper authentication.
- Review List Quality: Assess the quality and engagement of the recipient list to mitigate reputation damage.
- Investigate Microsoft's Filtering: Contact Microsoft sender support to explore the reasons behind filtering and potential solutions.
Expert view
Expert from Word to the Wise indicates that there are numerous possible reasons why email sent to Microsoft domains (Outlook, Hotmail, Live) gets blocked or filtered, ranging from IP reputation issues to content-related triggers, and the exact cause can be difficult to pinpoint without detailed investigation and working with Microsoft's sender support.
29 Mar 2022 - Word to the Wise
Expert view
Expert from Email Geeks suggests trying to send email through an SMTP server that's not Gmail for a while to see if that helps, as the Hubspot -> Gmail integration might be the problem.
17 Sep 2023 - Email Geeks
What the documentation says
4 technical articles
Emails sent from Gmail SMTP may land in Outlook, Hotmail, and Live spam folders for several documented reasons. Exceeding Gmail's sending limits can lead to throttling or spam classification by recipient servers. Outlook.com's specific policies on email filtering, especially regarding high complaint rates and spam-like content, can cause emails to be junked, even when sent via Gmail SMTP. Inadequate implementation of SPF, DKIM, and DMARC authentication methods can undermine trust in the email's origin. Finally, a lack of feedback loops to monitor spam complaints can result in a negative sender reputation, leading to spam folder placement.
Key findings
- Gmail Sending Limits: Exceeding Gmail's sending limits can lead to emails being marked as spam.
- Outlook.com Policies: Outlook.com has specific filtering policies, and violating them can lead to emails being sent to the junk folder.
- Authentication Issues: Improper implementation of SPF, DKIM, and DMARC can cause deliverability problems.
- Lack of Feedback Loops: Failure to monitor spam complaints can negatively impact sender reputation.
Key considerations
- Sending Limits: Adhere to Gmail's sending limits to avoid throttling or spam classification.
- Outlook.com Compliance: Review and comply with Outlook.com's email filtering policies.
- Authentication Verification: Ensure that SPF, DKIM, and DMARC are correctly implemented and configured.
- Feedback Loop Implementation: Set up feedback loops to monitor spam complaints and address any underlying issues.
Technical article
Documentation from Microsoft explains that Outlook.com has specific policies and practices regarding email filtering. If your emails violate these policies (e.g., high complaint rates, spam-like content), they are likely to be delivered to the junk folder. This applies to emails sent from Gmail SMTP.
9 Jul 2023 - Microsoft
Technical article
Documentation from Google Workspace Admin Help shares that exceeding Gmail's sending limits (number of recipients, daily sending limits) may cause emails to be throttled or marked as spam by recipient servers. Outlook, Hotmail and Live may view emails sent via Gmail SMTP in large volumes as potential spam.
23 Oct 2023 - Google Workspace Admin Help
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