> For the complete documentation index, see [llms.txt](https://docs.expel.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.expel.io/more-features/expel-managed-phishing/expel-auto-close-marketing-email.md).

# Expel Auto-Close Marketing Email

Expel Auto-Close Marketing Email (AME) reduces the time analysts spend triaging benign emails, by identifying and auto-closing emails related to marketing activities. This gives analysts more time to focus on triaging suspicious emails.

Marketing emails were specifically targeted for auto-identification because:

* They are largely recognizable to a human, so a machine can be taught what to look for.
* Expel receives a large volume of marketing emails (approximately 30% of our overall submissions are marketing emails).

## What Is Considered a Marketing Email?

Expel considers a variety of emails to be marketing email. Some examples include:

<div align="left"><figure><img src="/files/hzvHwEwDfNvoseUd5PLl" alt="Image of a marketing email with an event invitation." width="375"><figcaption></figcaption></figure></div>

<div align="left"><figure><img src="/files/t07Qis6X2l3Zurnfcomn" alt="Image of a marketing email with a survey link." width="334"><figcaption></figcaption></figure></div>

## What Does ​Expel AME Output?

​Expel AME returns four categories:

* Marketing
* Likely marketing
* Inconclusive
* Not marketing

Expel is conservative in what it confidently predicts as a marketing email, requiring **above 95% probability**.

<div align="left"><figure><img src="/files/ZuguiW7d4WrS54tWWs3M" alt="Image of a probability scale." width="563"><figcaption></figcaption></figure></div>

### What If I See an Email with ≥ 95% Marketing Probability in My Queue? Should It Be Auto-Closed?

In short, yes. But because of the configurations we have in place, and [our quality control (QC) process](#what-quality-checks-is-expel-doing), it is possible you see an email that would normally be closed, but was not.

Here are some additional details as to what scenarios have an email not auto-closed as marketing, even if it has a high probability of being a marketing email:

1. The email came from a newly onboarded customer.&#x20;
   * For these customers, Expel may delay turning on ​Expel AME until we are certain of how it performs for that specific customer.
2. The email did not pass the Expel post-processing rules.&#x20;
   * Post-processing rules are additional logic Expel adds before closing an email as marketing.
   * These rules allow Expel to make sure that emails which may be masking as marketing emails are reviewed by analysts and not auto-closed.&#x20;
   * Some example post-processing rules include: a marketing email was sent from a young domain, or the email was sent from a sender associated with previous malicious campaigns.

### What Factors Are Considered When Deciding If an Email is Marketing?

The following is a mostly complete list of items the model uses to make its predictions. The list was developed with our subject matter experts, our existing data sets, and the thousands of [Incidents](/workbench-reference/expel-terminology.md#incident) we have addressed.

{% hint style="info" %}
We are constantly updating and tweaking this list.
{% endhint %}

<table><thead><tr><th width="346.234375">Scenario</th><th>Determination</th></tr></thead><tbody><tr><td>Does the return path match the sender?</td><td>If the return path does not match the sender, the email is suspicious.</td></tr><tr><td>Is the sender domain associated with a previous malicious investigation?</td><td>If the sender domain is associated with a previous malicious investigation, this email is suspicious.</td></tr><tr><td>Is the subject tagged as marketing by upstream systems?</td><td>If an upstream system tagged this email as marketing, we incorporate this additional external knowledge.</td></tr><tr><td>Is the sender a corporate marketing account?</td><td>Professional marketing emails likely come from a marketing group within an organization.</td></tr><tr><td>Does the email contain an unsubscribe button?</td><td>Some marketing emails include an unsubscribe button.</td></tr><tr><td>Does the email have attachments?</td><td>Marketing emails are less likely to have attachments, instead opting for hyperlinks.</td></tr><tr><td>Does the email contain attachments that are common attack surfaces?</td><td>If the email contains attachments that are common attack surfaces, like spreadsheets or compressed files, it's more suspicious and less likely to be marketing.</td></tr><tr><td>Is the email sent from a personal email account?</td><td>Marketing emails are not likely to come from personal email accounts.</td></tr><tr><td>What Expel severity did the YARA rules decide on?</td><td>We include escalation logic derived from analyst experience, where High and Medium severity suggest that the email is suspicious.</td></tr><tr><td>Is the email sent from a corporation known to be abused by attackers?</td><td>PayPal, SharePoint, and DocuSign are platforms commonly abused by attackers, so emails from organizations can require additional oversight.</td></tr><tr><td>How many domains are linked to in the email?</td><td>A marketing email can reference more unique domains because these emails reference external content.</td></tr><tr><td>How many URLs are linked to in the email?</td><td>A marketing email can reference more unique URLs because these emails reference external content and often contain unique identifiers.</td></tr><tr><td>How many marketing-related terms are in the email body?</td><td>Marketing phrases and products (such as webinars, white papers) are clearly advertised in the subject line.</td></tr><tr><td>How many marketing-related terms are in the subject?</td><td>Marketing phrases and products (such as webinars, white papers) are clearly advertised in the subject line.</td></tr><tr><td>How colorful is the email screenshot?</td><td>Some types of marketing emails can be very colorful.</td></tr><tr><td>How long is the email?</td><td>Shorter emails are more likely to be marketing.</td></tr><tr><td>How many explicit terms are used throughout the email body?</td><td>Marketing emails tend to not include explicit terminology.</td></tr><tr><td>What is the sender domain age?</td><td>Newly registered domains tend to be suspicious.</td></tr><tr><td>Can we represent the entire email body with text embeddings?</td><td>If we capture semantic relations within an email body, we can differentiate email categories based on how the email was written.</td></tr></tbody></table>

### What Quality Checks Is Expel Doing?

Expel uses multiple quality control (QC) processes to ensure ​Expel AME only auto-closes benign marketing emails.

* Expel randomly turns off auto-close for a sample of highly probable marketing emails, and redirects these emails to be triaged by senior analysts. This is done to compare the decision made by a senior analyst to how the model triaged the email. We use these comparisons to monitor our model and the results it’s producing.
* Expel uses [Arthur AI](https://www.arthur.ai/) to watch the model in production. With Arthur AI, we look at the inputs and outputs of the model to see if there is a drift in the data. Data drift is a leading indicator of potential performance degradation of the model.

<div align="left"><figure><img src="/files/Oy7OBF78jPu3TOwU6FHu" alt="Image of the Expel monitoring flow." height="251" width="624"><figcaption></figcaption></figure></div>

### How Can I Give Feedback?

We are always looking for ways to improve! For a model feature request or an analytics ad-hoc, reach out to our [support team](/support/how-to-reach-us.md).


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