diff --git a/CHANGELOG.md b/CHANGELOG.md
index ad27eab7..81cfe6ef 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,8 +1,9 @@
 # Nylas Java SDK Changelog
 
-## Unreleased
+### [Unreleased]
 
 ### Added
+* Added support for custom headers field for Drafts and Messages
 * Added support for overriding various fields of outgoing requests
 
 ## [2.2.1] - Released 2024-03-05
diff --git a/src/main/kotlin/com/nylas/models/CreateDraftRequest.kt b/src/main/kotlin/com/nylas/models/CreateDraftRequest.kt
index 8965bd5a..4eea7194 100644
--- a/src/main/kotlin/com/nylas/models/CreateDraftRequest.kt
+++ b/src/main/kotlin/com/nylas/models/CreateDraftRequest.kt
@@ -62,6 +62,11 @@ data class CreateDraftRequest(
    */
   @Json(name = "tracking_options")
   val trackingOptions: TrackingOptions? = null,
+  /**
+   * A list of custom headers to add to the message.
+   */
+  @Json(name = "custom_headers")
+  val customHeaders: List<CustomHeader>? = null,
 ) : IMessageAttachmentRequest {
   /**
    * Builder for [CreateDraftRequest].
@@ -78,6 +83,7 @@ data class CreateDraftRequest(
     private var sendAt: Int? = null
     private var replyToMessageId: String? = null
     private var trackingOptions: TrackingOptions? = null
+    private var customHeaders: List<CustomHeader>? = null
 
     /**
      * Sets the recipients.
@@ -157,6 +163,13 @@ data class CreateDraftRequest(
      */
     fun trackingOptions(trackingOptions: TrackingOptions?) = apply { this.trackingOptions = trackingOptions }
 
+    /**
+     * Sets the custom headers to add to the message.
+     * @param customHeaders The custom headers to add to the message.
+     * @return The builder.
+     */
+    fun customHeaders(customHeaders: List<CustomHeader>?) = apply { this.customHeaders = customHeaders }
+
     /**
      * Builds a [SendMessageRequest] instance.
      * @return The [SendMessageRequest] instance.
@@ -174,6 +187,7 @@ data class CreateDraftRequest(
         sendAt,
         replyToMessageId,
         trackingOptions,
+        customHeaders,
       )
   }
 }
diff --git a/src/main/kotlin/com/nylas/models/CustomHeader.kt b/src/main/kotlin/com/nylas/models/CustomHeader.kt
new file mode 100644
index 00000000..b8cd9b18
--- /dev/null
+++ b/src/main/kotlin/com/nylas/models/CustomHeader.kt
@@ -0,0 +1,36 @@
+package com.nylas.models
+
+import com.squareup.moshi.Json
+
+/**
+ * Custom headers to be used when drafting or sending an email.
+ */
+data class CustomHeader(
+  /**
+   * The name of the custom header.
+   */
+  @Json(name = "name")
+  val name: String,
+  /**
+   * The value of the custom header.
+   */
+  @Json(name = "value")
+  val value: String,
+) {
+  /**
+   * Builder for [CustomHeader].
+   * @property name The name of the custom header.
+   * @property value The value of the custom header.
+   */
+  data class Builder(
+    private val name: String,
+    private val value: String,
+  ) {
+    /**
+     * Build the [CustomHeader] object.
+     */
+    fun build(): CustomHeader {
+      return CustomHeader(name, value)
+    }
+  }
+}
diff --git a/src/main/kotlin/com/nylas/models/SendMessageRequest.kt b/src/main/kotlin/com/nylas/models/SendMessageRequest.kt
index f091f269..fee41f45 100644
--- a/src/main/kotlin/com/nylas/models/SendMessageRequest.kt
+++ b/src/main/kotlin/com/nylas/models/SendMessageRequest.kt
@@ -68,6 +68,11 @@ data class SendMessageRequest(
    */
   @Json(name = "use_draft")
   val useDraft: Boolean? = null,
+  /**
+   * A list of custom headers to add to the message.
+   */
+  @Json(name = "custom_headers")
+  val customHeaders: List<CustomHeader>? = null,
 ) : IMessageAttachmentRequest {
   /**
    * Builder for [SendMessageRequest].
@@ -87,6 +92,7 @@ data class SendMessageRequest(
     private var replyToMessageId: String? = null
     private var trackingOptions: TrackingOptions? = null
     private var useDraft: Boolean? = null
+    private var customHeaders: List<CustomHeader>? = null
 
     /**
      * Sets the bcc recipients.
@@ -167,6 +173,13 @@ data class SendMessageRequest(
      */
     fun useDraft(useDraft: Boolean?) = apply { this.useDraft = useDraft }
 
+    /**
+     * Sets the custom headers to add to the message.
+     * @param customHeaders The custom headers to add to the message.
+     * @return The builder.
+     */
+    fun customHeaders(customHeaders: List<CustomHeader>?) = apply { this.customHeaders = customHeaders }
+
     /**
      * Builds a [SendMessageRequest] instance.
      * @return The [SendMessageRequest] instance.
@@ -185,6 +198,7 @@ data class SendMessageRequest(
         replyToMessageId,
         trackingOptions,
         useDraft,
+        customHeaders,
       )
   }
 }
diff --git a/src/test/kotlin/com/nylas/resources/DraftsTests.kt b/src/test/kotlin/com/nylas/resources/DraftsTests.kt
index 2d71b280..eb774273 100644
--- a/src/test/kotlin/com/nylas/resources/DraftsTests.kt
+++ b/src/test/kotlin/com/nylas/resources/DraftsTests.kt
@@ -230,6 +230,7 @@ class DraftsTests {
           sendAt = 1620000000,
           replyToMessageId = "reply-to-message-id",
           trackingOptions = TrackingOptions(label = "label", links = true, opens = true, threadReplies = true),
+          customHeaders = listOf(CustomHeader(name = "header", value = "value")),
         )
 
       drafts.create(grantId, createDraftRequest)
@@ -275,6 +276,7 @@ class DraftsTests {
               size = 100,
             ),
           ),
+          customHeaders = listOf(CustomHeader(name = "header", value = "value")),
         )
 
       drafts.create(grantId, createDraftRequest)
@@ -320,6 +322,7 @@ class DraftsTests {
               size = 3 * 1024 * 1024,
             ),
           ),
+          customHeaders = listOf(CustomHeader(name = "header", value = "value")),
         )
 
       drafts.create(grantId, createDraftRequest)
diff --git a/src/test/kotlin/com/nylas/resources/MessagesTests.kt b/src/test/kotlin/com/nylas/resources/MessagesTests.kt
index dd5df73b..f98e27dc 100644
--- a/src/test/kotlin/com/nylas/resources/MessagesTests.kt
+++ b/src/test/kotlin/com/nylas/resources/MessagesTests.kt
@@ -384,6 +384,7 @@ class MessagesTests {
           sendAt = 1620000000,
           replyToMessageId = "reply-to-message-id",
           trackingOptions = TrackingOptions(label = "label", links = true, opens = true, threadReplies = true),
+          customHeaders = listOf(CustomHeader(name = "header-name", value = "header-value")),
         )
 
       messages.send(grantId, sendMessageRequest)
@@ -430,6 +431,7 @@ class MessagesTests {
               size = 100,
             ),
           ),
+          customHeaders = listOf(CustomHeader(name = "header-name", value = "header-value")),
         )
 
       messages.send(grantId, sendMessageRequest)
@@ -476,6 +478,7 @@ class MessagesTests {
               size = 3 * 1024 * 1024,
             ),
           ),
+          customHeaders = listOf(CustomHeader(name = "header-name", value = "header-value")),
         )
 
       messages.send(grantId, sendMessageRequest)