Summary
To format Feedback-ID for Gmail effectively, use up to four identifiers separated by colons in the format `Feedback-ID: A:B:C:D`, although not all identifiers are always available. Read these in reverse (D to A), with 'D' identifying the ESP/Platform, 'C' the Account, 'B' the Mail Stream/List, and 'A' the Specific Mailing, though A and B often return nothing. Ensure identifiers are relevant, unique, and consistently formatted to enable effective feedback loop analysis, pinpoint issues, and improve deliverability by tracking complaints. Prioritize user privacy by anonymizing or hashing identifiers, avoiding PII. While Feedback-ID aids in troubleshooting, it cannot overcome a bad sender reputation; a solid reputation is crucial for its effectiveness. Google bases identifier importance on the volume of complaint data.
Key findings
- Format Structure: Feedback-ID utilizes up to four identifiers (A:B:C:D) separated by colons, read in reverse order.
- Identifier Purpose: 'D' is for ESP/Platform, 'C' is for Account, 'B' is for Mail Stream/List, and 'A' is for Specific Mailing.
- Availability Variances: Not all identifiers are always available, and 'A' and 'B' often return no data.
- Deliverability Impact: Correctly formatted Feedback-ID improves deliverability and enables effective tracking of complaints for pinpointing issues.
- Google's Usage: Google bases identifier importance on the volume of complaint data associated with each.
Key considerations
- Consistency & Relevance: Ensure consistent formatting and relevance of identifiers for effective analysis.
- Uniqueness of IDs: Leverage meaningful, trackable, and unique identifiers related to the mailing, campaign, or account.
- Privacy Protection: Prioritize user privacy by anonymizing or hashing identifiers, and avoid including PII.
- Sender Reputation: Feedback-ID is most effective when combined with a solid sender reputation; it cannot overcome a poor one.
- Stripping of Unique IDs: Be aware that Google might strip out anything that appears to be a unique identifier.
What email marketers say
11 marketer opinions
Feedback-ID for Gmail should be formatted using four variable slots (A:B:C:D), typically read in reverse order (D to A). 'D' identifies the sending platform/ESP, 'C' the account, 'B' the mail stream/list, and 'A' the specific mailing. However, 'A' and 'B' often return nothing. Correct formatting improves deliverability by tracking complaint data, pinpointing issues, and enabling corrective actions. Consistent formatting, meaningful identifiers (campaign ID, customer ID, mailing ID), and ensuring no reverse identification of complainers are key. Google bases identifier importance on the volume of complaint data. The IDs can be used to track complaints and the more unique they are the better to track individual responses.
Key opinions
- Variable Slots: The Feedback-ID supports four variable slots: A:B:C:D.
- Reading Order: Typically read in reverse order, from D to A.
- Identifier Meaning: D: Sending Platform/ESP, C: Account, B: Mail Stream/List, A: Specific Mailing.
- Deliverability Impact: Improves deliverability by tracking complaints and enabling corrective actions.
- Identifier Returns: A and B variables often return nothing.
Key considerations
- Consistency: Maintain a consistent format across all mailings.
- Meaningful Identifiers: Use meaningful and trackable identifiers (campaign ID, customer ID, mailing ID).
- Complaint Data: Google bases identifier importance on the volume of complaint data.
- Privacy: Avoid including Personally Identifiable Information to prevent reverse identification of complainers.
Marketer view
Email marketer from Validity explains that Feedback-ID best practices include using a consistent format across all mailings and ensuring that the identifiers used are meaningful and trackable. They recommend using a combination of identifiers such as campaign ID, customer ID, and mailing ID to maximize the effectiveness of the Feedback-ID.
4 Aug 2021 - Validity
Marketer view
Email marketer from Email Geeks explains that Google seems to base this on the volume of data they have for each identifier in terms of the number of complaints.
13 Jan 2023 - Email Geeks
What the experts say
4 expert opinions
Experts recommend focusing on privacy and sender reputation when formatting Feedback-ID. Not all four identifiers are always available, and unique IDs might be stripped. Alternatives to the standard format exist. Data should be anonymized or hashed to protect user privacy. A solid sender reputation is crucial for Feedback-ID to be effective in troubleshooting delivery issues when Gmail's spam filter misclassifies messages.
Key opinions
- Identifier Availability: Not all four Feedback-ID identifiers (A:B:C:D) are always available; only 1 or 2 may be present.
- Unique ID Stripping: Gmail may strip out anything that looks like a unique identifier from the Feedback-ID.
- Alternative Format: Alternative Feedback-ID formats can be used, such as ClientID:YYYYMMDD_HH:MailType:Platform.
- Privacy Importance: It's crucial to ensure that the data included doesn't compromise user privacy; anonymize or hash identifiers.
- Reputation Impact: A solid sender reputation is necessary for Feedback-ID to be effective with Gmail.
Key considerations
- Privacy Compliance: Prioritize anonymizing or hashing data to comply with privacy regulations.
- Sender Reputation: Focus on building a good sender reputation as Feedback-ID is most effective when combined with a positive reputation.
- Format Flexibility: Be flexible with the Feedback-ID format, as not all fields may be available.
- Delivery Troubleshooting: Use Feedback-ID as a diagnostic tool for misclassified messages, but address reputation issues first.
Expert view
Expert from Word to the Wise (Laura Atkins) responds that Feedback-ID is a helpful diagnostic tool when the Gmail spam filter is misclassifying messages, but it can't overcome a bad sender reputation. Senders need to establish a solid reputation before Gmail starts actively using it. However, once this is done, feedback from Feedback-ID becomes really important for troubleshooting delivery issues.
25 Jun 2021 - Word to the Wise
Expert view
Expert from Email Geeks explains that they don't usually get all 4 identifiers, maybe 1 or 2 regularly and anything that looks like it could be a unique ID will be stripped.
9 Jan 2025 - Email Geeks
What the documentation says
3 technical articles
Documentation emphasizes using up to four identifiers separated by colons in the Feedback-ID header (`Feedback-ID: a:b:c:d`). This provides a structured way to identify specific mailings, track complaints, and troubleshoot deliverability. Consistency and relevance of identifiers are crucial for effective feedback loop analysis. Unique identifiers related to mailing, campaign, or account are recommended.
Key findings
- Format: Feedback-ID uses up to four identifiers separated by colons.
- Purpose: It's intended for feedback loops to identify mailings and track complaints.
- Troubleshooting: Assists in pinpointing the origin of emails and troubleshooting deliverability.
- Identifiers: Letters represent different identifiers, like a mailing ID, campaign ID, or customer ID.
Key considerations
- Consistency: Maintain consistent order of identifiers.
- Relevance: Ensure each identifier is relevant and helps in identification.
- Uniqueness: Use unique identifiers related to the mailing, campaign, or account.
- Analysis: Select identifiers that allow for effective feedback loop analysis.
Technical article
Documentation from SparkPost explains that when implementing Feedback-ID, it is crucial to maintain consistency in the order of identifiers and to ensure that each identifier is relevant and helps in the identification process. They recommend using identifiers that are unique to the mailing, campaign, or account to allow for effective feedback loop analysis.
21 May 2022 - SparkPost
Technical article
Documentation from RFC-8260 describes that the Feedback-ID header field is intended to provide a structured method for feedback loops to identify specific mailings and track complaints. It allows for the inclusion of several identifiers to pinpoint the origin of the email and assist in troubleshooting deliverability issues.
13 Feb 2024 - RFC-8260
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