> For the complete documentation index, see [llms.txt](https://docs.mailtrap.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.mailtrap.io/email-api-smtp/deliverability/feedback-loops.md).
# Feedback Loops
Learn how Mailtrap integrates with popular Feedback Loops (FBLs) to track spam complaints from major mailbox providers including Outlook, Yahoo, and more.
Mailtrap is integrated with the majority of popular Feedback Loops (FBLs) to gather information about spam complaints.
{% hint style="info" %}
Remember that Gmail doesn’t provide spam complaint information per message.
{% endhint %}
Still, Mailtrap adds `Feedback-ID` to all emails sent to Gmail. If you specify Email Categories, we add it to the header as a part of the category. Yet, it’s up to Gmail to show that info in your Google Postmaster. Read more about the feedback header [here](https://support.google.com/a/answer/6254652?hl=en).
Our Deliverability Team can review aggregated data for Spam Rates for Gmail recipients daily if you provide us with view rights for Google Postmaster. This service is available for our paid customers. Please contact our support team for the details.
Contact Support
The list of FBLs Mailtrap is integrated with:
* Microsoft Outlook
* Yahoo! Mail
* Bluetie
* Comcast
* Fastmail
* gandi.net
* Liberty Global (Chello, UPC, and UnityMedia)
* Locaweb
* Mail.ru
* OpenSRS/Hostedmail (Tucows)
* Rackspace
* Seznam
* SFR
* SilverSky
* Swisscom
* Synacor
* Telecom Italia
* Telenet
* Telenor
* Telstra
* Terra
* UOL
* Virgilio
* Virgin Media
* Yandex
* Ziggo
While using our services, Mailtrap may get alerts from these FBLs if your recipients submit spam complaints. You'll see them in your [Stats](/email-api-smtp/analytics/dashboard.md) and may receive them via [Webhooks](/email-api-smtp/setup/sending-domain.md#optional-webhooks-4hmes).
We also support the `CFBL-Address` header as per [RFC 9477](https://www.rfc-editor.org/rfc/rfc9477.html). However, it’s still experimental, and not all mailbox providers support it.
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# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.
## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation by asking a question.
Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:
```
GET https://docs.mailtrap.io/email-api-smtp/deliverability/feedback-loops.md?ask=&goal=
```
`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.