Why does SFMC show email as delivered when it's not in inbox, spam or quarantine?

Key findings

• SFMC's definition: SFMC typically marks an email as delivered once the recipient's Mail Transfer Agent (MTA) has accepted it. This is a common practice across many Email Service Providers (ESPs).
• Recipient server processing: After acceptance, the recipient's server (or even an Office 365 tenant's specific settings) performs its own spam analysis, filtering, and routing. An email can be held in a recipient's mail quarantine, processed for spam analysis, or silently deleted if its spam score is too high. This is particularly true for Microsoft domains, which might discard emails with high spam scores without notifying the sender.
• Delayed delivery: Some Mailbox Providers (MBPs), like Google, strive to deliver all accepted emails eventually, even if it means significant delays (sometimes hours). Salesforce Stack Exchange mentions this behavior.
• User-level filters: Individual user settings and automated inbox rules can sort messages into different folders, or even delete them, after the server has initially accepted them.
• Temporary deferrals: SFMC may show an email as delivered even if it's temporarily deferred, with the delivery rate potentially dropping later if the 72-hour retry period expires. For further insights into such discrepancies, explore our article on resolving SFMC reporting discrepancies.

Key considerations

• Inbox placement monitoring: Reliance solely on ESP 'delivered' metrics is insufficient. True email deliverability means reaching the inbox. Understanding this difference is key to solving missing emails, as detailed in our guide on why emails aren't appearing.
• Sender reputation impact: A low sender reputation can lead to increased filtering by recipient servers, resulting in silent drops or quarantine. This aligns with what Salesforce Ben highlights regarding inbox placement versus ending up in spam.
• Internal IT collaboration: For organizations managing their own Exchange servers, IT teams can investigate email logs from the moment an email hits the MX record to determine its journey and eventual fate. This is often the most reliable way to diagnose silent drops.
• Content and engagement: Email content, especially for industries like pharmaceuticals, can inherently trigger spam filters due to length or keywords. User engagement (or lack thereof) also plays a significant role in how future emails are delivered.

Key opinions

• Definition of delivery: Marketers frequently express confusion because "delivered" in SFMC means the email was accepted by the recipient's MTA, not that it reached the user's desired folder.
• Microsoft's behavior: Many marketers specifically call out Microsoft domains and Office 365 tenants for silently discarding emails with high spam scores or applying strict individual filters, leading to emails going missing. This aligns with our observation on emails not delivering to Microsoft inboxes.
• Troubleshooting difficulty: It is acknowledged that diagnosing deliverability issues for a few specific messages can be challenging due to the many stages an email goes through after leaving the ESP. This is a common pain point for SFMC emails showing as delivered but not received.
• Content sensitivity: Some industries, like pharmaceuticals, face inherent content-related challenges, as their email length or specific terms can automatically trigger spam filters at the recipient's end.
• Reliance on IT: Marketers often depend on their internal IT teams to investigate issues within their managed Exchange servers, though getting IT to acknowledge and prioritize these issues can be difficult.

Key considerations

• Proactive monitoring: Marketers should adopt tools and strategies that go beyond ESP delivery reports to monitor actual inbox placement and identify potential filtering issues. Salesforce Ben discusses optimizing deliverability.
• Strengthening sender reputation: Focusing on best practices for list hygiene, email authentication (SPF, DKIM, DMARC), and engagement can improve sender reputation and reduce the likelihood of silent drops or spam folder placement.
• Internal advocacy: Providing clear, concise information and evidence to IT teams can help them understand and address email delivery problems within the corporate network.
• Content optimization: Even with challenging content, optimizing subject lines, preheader text, and the email body for less spam trigger words can help improve inbox placement.

Key opinions

• MTA handshake: Experts confirm that SFMC's "delivered" status signifies the successful hand-off to the recipient's MTA, not necessarily placement in the user's mailbox. This is a crucial distinction for accurate troubleshooting.
• Post-acceptance processing: After accepting an email, recipient servers queue messages, hold them for quarantine, or subject them to spam analysis. This process can lead to messages disappearing from view even after they've been 'delivered' by the ESP.
• MBP variations: Different mailbox providers handle emails differently. Google tends to eventually deliver accepted emails (though with potential delays), while Microsoft (including Office 365) may silently drop emails if the spam score is too high.
• User filters and behavior: Beyond server-level filtering, individual user filters and behavior-based delivery rules can also route or delete emails without explicit bounces. This highlights the complexity of inbox placement. Read more about missing or silently dropped emails.
• Comprehensive logging: For self-managed Exchange servers, experts advise that IT teams should be able to track the full email process from the moment it hits the MX record, providing crucial diagnostic data for unseen filtering.

Key considerations

• Beyond delivery metrics: Experts strongly recommend looking beyond ESP-reported delivery rates to actual inbox placement. Tools that provide insight into where emails land after server acceptance are vital.
• Understanding recipient infrastructure: It's essential to understand that different recipient infrastructures, especially Google versus Microsoft, have unique approaches to email filtering and delivery. This influences how likely emails are to be delayed or silently dropped.
• Leveraging IT resources: For organizations with in-house mail servers, close collaboration with the IT team is critical. They possess the logs and control over filters that can reveal why emails are disappearing internally.
• Holistic troubleshooting: Given the many potential points of failure or filtering, troubleshooting missing emails requires a holistic approach, considering sender reputation, content, authentication, and recipient server behavior. Learn more about improving email deliverability.

Key findings

• ESP delivery definition: Documentation for ESPs, including SFMC, generally defines 'delivered' as the successful transfer of the email from their server to the recipient's Mail Exchange (MX) server. This signifies the end of the ESP's responsibility for the email's journey. Salesforce's documentation suggests that if an email doesn't bounce, it's considered delivered.
• Recipient server processing: Mailbox Providers (MBPs) like Google and Microsoft detail complex filtering processes that occur after initial acceptance. These processes include spam filtering, virus scanning, and policy enforcement, which can lead to emails being placed in spam, quarantined, or discarded.
• DMARC policy impact: DMARC documentation indicates that a 'quarantine' or 'reject' policy, if enforced by the recipient domain, can lead to emails failing DMARC checks being moved to spam or discarded entirely. This happens without a bounce notification to the original sender.
• Inbox placement vs. delivery: Official resources often differentiate between email 'delivery' (server-to-server transfer) and 'inbox placement' (the email landing in the primary inbox), acknowledging that the former doesn't guarantee the latter.
• Sender reputation metrics: Documentation from major MBPs, such as Google Postmaster Tools, emphasizes the role of sender reputation, spam complaints, and authentication (SPF, DKIM, DMARC) in determining inbox placement. Poor reputation metrics can lead to emails being filtered out. See our guide to Google Postmaster Tools.

Key considerations

• Authentication compliance: Ensure SPF, DKIM, and DMARC are correctly configured and aligned, as non-compliance is a major reason for filtering. Digital Marketing on Cloud highlights that an SPF failure means Outlook couldn't verify the sending server.
• Reviewing MBP guidelines: Regularly review specific guidelines from major mailbox providers (e.g., Gmail's bulk sender guidelines, Microsoft's anti-spam policies) to understand their filtering criteria and best practices.
• Monitoring DMARC reports: Utilize DMARC reports to gain visibility into how recipient servers are handling emails that fail authentication. This can reveal if emails are being quarantined or rejected due to policy enforcement. More on this in our DMARC reports guide.
• Content best practices: Adhere to content best practices to avoid triggering spam filters, which can result in emails being shunted to spam folders or silently dropped even if authentication passes.