---
title: "Mark Email As Read"
slug: "mark-email-as-read"
updated: 2025-08-29T19:21:45Z
published: 2025-08-29T19:21:45Z
canonical: "documentation.decisions.com/mark-email-as-read"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://documentation.decisions.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Mark Email As Read

| Step Details |
| --- |
| **Introduced in Version** | 4.0.0 |
| **Last Modified in Version** | 9.10.0 |
| **Location** | Integration > Microsoft365 > Exchange > Email |

The **Mark Email as Read** step marks a specified email as read from a Microsoft365 Exchange email account.

### Prerequisites

- This step requires the [Microsoft 365 Exchange](https://documentation.decisions.com/docs/microsoft365-exchange) module to be [installed](https://documentation.decisions.com/docs/installing-modules-decisions) before it will be available in the toolbox.
- A [dependency](https://documentation.decisions.com/docs/project-dependencies) must be created after installing the module in order for the the steps to be properly used.

---

## Properties

#### Inputs

| Property | Description | Data Type |
| --- | --- | --- |
| Message Id | ID of message to mark as read. | String |
| User Identifier | Identifier of user to associate with marking as read. | String |

#### Settings

| Property | Description | Data Type |
| --- | --- | --- |
| Settings Override | Optional settings to override default OAuth token. | InputExchangeSettings |

#### Outputs

| Property | Description | Data Type |
| --- | --- | --- |
| Output | The part of the string that was extracted. | String |

![](https://cdn.document360.io/6ef8bcc1-6489-4486-9ad1-83acff7e5df0/Images/Documentation/image-1753211655801.png)

---

## Common Errors

### Data Not Mapped Correctly

If the inputs are incorrectly formatted, the step will cause an error. To correct this, input valid inputs to permit proper orderly operations.

#### Exception Message:

```csharp
Exception Stack Trace: DecisionsFramework.Design.Flow.ErrorRunningFlowStep: Error running step Substring 1[Substring] in flow [Display Steps]: Exception invoking method Substring on class StringSteps 
 ---> DecisionsFramework.LoggedException: Exception invoking method Substring on class StringSteps 
 ---> System.ArgumentOutOfRangeException: Index and length must refer to a location within the string. (Parameter 'length')  
   at System.String.Substring(Int32 startIndex, Int32 length)       
   --- End of inner exception stack trace ---  
   at DecisionsFramework.Design.Flow.StepImplementations.InvokeMethodStep.Run(StepStartData data  at DecisionsFramework.Design.Flow.FlowStep.RunStepInternal(String flowTrackingID, String stepTrackingID, KeyValuePairDataStructure[] stepRunDataValues, AbstractFlowTrackingData trackingData)  
   at DecisionsFramework.Design.Flow.FlowStep.Start(String flowTrackingID, String stepTrackingID, FlowStateData data, AbstractFlowTrackingData trackingData, RunningStepData currentStepData)       
   --- End of inner exception stack trace ---
```

### The Request Was Unsuccessful.

If the token defined cannot be used to access Microsoft Exchange, the step will cause an error. To correct this, ensure a correct and valid OAuth token has been established.

#### Exception Message:

```csharp
DecisionsFramework.BusinessRuleException: [BusinessRule] The request was unsuccessful. ---> System.Net.Http.HttpRequestException: Response status code does not indicate success: 401 (Unauthorized).
at System.Net.Http.HttpResponseMessage.EnsureSuccessStatusCode()
at Decisions.Microsoft365.Exchange.GraphRest.SendHttpRequest(ExchangeSettings settingsOverride, String url, HttpContent content, HttpMethod httpMethod)
--- End of inner exception stack trace ---
at Decisions.Microsoft365.Exchange.GraphRest.SendHttpRequest(ExchangeSettings settingsOverride, String url, HttpContent content, HttpMethod httpMethod)
at Decisions.Microsoft365.Exchange.GraphRest.CreateHttpRequest(ExchangeSettings settingsOverride, String urlExtension, HttpContent content, HttpMethod httpMethod)
at Decisions.Microsoft365.Exchange.GraphRest.HttpResponsePost(ExchangeSettings settingsOverride, String urlExtension, HttpContent content)
at Decisions.Microsoft365.Exchange.GraphRest.Post(ExchangeSettings settingsOverride, String urlExtension, HttpContent content)
at Decisions.Microsoft365.Exchange.Steps.ExchangeCalenderSteps.CreateCalendarEvent(Microsoft365CalendarEvent microsoft365CalendarEvent, String userIdentifier, String calendarId, InputExchangeSettings settingsOverride)
at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
at System.Reflection.MethodBaseInvoker.InvokeDirectByRefWithFewArgs(Object obj, Span`1 copyOfArgs, BindingFlags invokeAttr)
```

---

Related Information

Related Articles: [Exchange Web Services Module](https://documentation.decisions.com/docs/microsoft365-exchange)