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Why are SNDS and SFMC reports showing discrepancies in email delivery data, and how to resolve it?

Summary

Discrepancies between Microsoft's SNDS (Smart Network Data Services) and Salesforce Marketing Cloud (SFMC) reports regarding email delivery data are a common challenge for email marketers, particularly during IP warming. While SFMC might indicate emails as 'delivered', SNDS can show significantly lower receipt volumes (RCPT and DATA columns), or even no data at all for a period when blocks occurred. This divergence often leads to confusion, as marketers struggle to reconcile their sending platform's success metrics with the insights provided by the recipient domain's postmaster tools.

What email marketers say

Email marketers often find themselves in a challenging position when their sending platform's delivery metrics don't align with the data reported by postmaster tools like SNDS. This can be particularly frustrating when trying to understand deliverability to major ISPs like Microsoft. Marketers frequently rely on their ESP's 'delivered' status, but then find that SNDS shows a different picture, leading to confusion about where emails are truly landing, if at all. The lack of transparent reconciliation from ESPs on these discrepancies can further complicate troubleshooting efforts.

Marketer view

An Email Geeks marketer noted that after being blocked, their SNDS data showed significantly lower RCPT and DATA volumes than their 10,000 daily sending volume to Microsoft, even though SFMC reported deliveries. This suggests an issue beyond simple bounces, potentially with how Microsoft processes or reports accepted mail.

07 Jan 2020 - Email Geeks

Marketer view

A deliverability professional from Email Geeks mentioned that sometimes SNDS data is simply missing, implying that not all deliverability events are consistently recorded or presented in the tool.

08 Jan 2020 - Email Geeks

What the experts say

Deliverability experts often point out that the reporting mechanisms of ESPs and recipient-side postmaster tools operate at different points in the email delivery chain, which naturally leads to discrepancies. While an ESP's 'delivered' status typically means the email was accepted at the SMTP handshake, a postmaster tool like SNDS provides insight into what happened after that point, including internal filtering, spam folder placement, or even 'silent drops' where messages are accepted but never truly processed for delivery to the inbox or spam folder. Understanding these nuances is crucial for accurate troubleshooting and maintaining sender reputation.

Expert view

A deliverability expert from Word to the Wise suggests that an ESP's reported delivery rate merely indicates successful SMTP hand-off, not necessarily inbox placement. Discrepancies arise because recipient servers can still filter or discard mail after acceptance, which won't be reflected in the sender's logs.

15 Feb 2024 - Word to the Wise

Expert view

An Email Geeks deliverability professional stated that they have observed more cases of 'silent drops' at Microsoft lately, where the DATA column in SNDS does not reflect the full volume sent. They noted this indicates a processing issue beyond typical SMTP bounces.

11 Jan 2020 - Email Geeks

What the documentation says

Official documentation from email service providers (ESPs) and ISPs outlines how delivery data is collected and presented. SFMC's 'delivered' status generally means the email was successfully handed off to the recipient's mail server via SMTP. Microsoft's SNDS, on the other hand, provides insights from the receiving end, including volume of messages processed, spam complaints, and reputation status. The discrepancies often arise from the different stages of processing an email goes through once accepted by the receiving server, which may include internal filtering, deferrals, or discarding before actual inbox delivery.

Technical article

Microsoft's Smart Network Data Services (SNDS) documentation specifies that the DATA column represents the count of messages that were successfully transferred via SMTP and processed by their systems. Discrepancies with sending ESPs often arise if mail is accepted but then filtered internally before full processing.

12 Mar 2023 - Microsoft Documentation

Technical article

The Salesforce Marketing Cloud documentation on email delivery states that an email is considered 'delivered' once the receiving mail server sends back a 250 OK response, signifying successful receipt of the message. This is a crucial distinction, as it doesn't guarantee inbox placement.

01 Jan 2024 - Salesforce Documentation

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