diff --git a/emails.go b/emails.go
index d125e58..3372954 100644
--- a/emails.go
+++ b/emails.go
@@ -64,19 +64,25 @@ type Attachment struct {
 	// Path where the attachment file is hosted instead of providing the
 	// content directly.
 	Path string
+
+	// Content type for the attachment, if not set will be derived from
+	// the filename property
+	ContentType string
 }
 
 // MarshalJSON overrides the regular JSON Marshaller to ensure that the
 // attachment content is provided in the way Resend expects.
 func (a *Attachment) MarshalJSON() ([]byte, error) {
 	na := struct {
-		Content  []int  `json:"content,omitempty"`
-		Filename string `json:"filename,omitempty"`
-		Path     string `json:"path,omitempty"`
+		Content     []int  `json:"content,omitempty"`
+		Filename    string `json:"filename,omitempty"`
+		Path        string `json:"path,omitempty"`
+		ContentType string `json:"content_type,omitempty"`
 	}{
-		Filename: a.Filename,
-		Path:     a.Path,
-		Content:  BytesToIntArray(a.Content),
+		Filename:    a.Filename,
+		Path:        a.Path,
+		Content:     BytesToIntArray(a.Content),
+		ContentType: a.ContentType,
 	}
 	return json.Marshal(na)
 }
diff --git a/emails_test.go b/emails_test.go
index 72d5723..f238668 100644
--- a/emails_test.go
+++ b/emails_test.go
@@ -70,7 +70,7 @@ func TestSendEmailWithAttachment(t *testing.T) {
 		if err != nil {
 			t.Errorf("failed to read request body: %v", err)
 		}
-		exp := `"attachments":[{"content":[104,101,108,108,111],"filename":"hello.txt"}]`
+		exp := `"attachments":[{"content":[104,101,108,108,111],"filename":"hello.txt","content_type":"text/plain"}]`
 		if !bytes.Contains(content, []byte(exp)) {
 			t.Errorf("request body does not include attachment data")
 		}
@@ -87,8 +87,9 @@ func TestSendEmailWithAttachment(t *testing.T) {
 		To: []string{"d@e.com"},
 		Attachments: []*Attachment{
 			{
-				Content:  []byte("hello"),
-				Filename: "hello.txt",
+				Content:     []byte("hello"),
+				Filename:    "hello.txt",
+				ContentType: "text/plain",
 			},
 		},
 	}
diff --git a/examples/with_attachments.go b/examples/with_attachments.go
index c225e8c..aced7e8 100644
--- a/examples/with_attachments.go
+++ b/examples/with_attachments.go
@@ -27,13 +27,15 @@ func withAttachments() {
 
 	// Create attachments objects
 	pdfAttachmentFromLocalFile := &resend.Attachment{
-		Content:  f,
-		Filename: "invoice1.pdf",
+		Content:     f,
+		Filename:    "invoice1.pdf",
+		ContentType: "application/pdf",
 	}
 
 	pdfAttachmentFromRemotePath := &resend.Attachment{
-		Path:     "https://github.com/resend/resend-go/raw/main/resources/invoice.pdf",
-		Filename: "invoice2.pdf",
+		Path:        "https://github.com/resend/resend-go/raw/main/resources/invoice.pdf",
+		Filename:    "invoice2.pdf",
+		ContentType: "application/pdf",
 	}
 
 	params := &resend.SendEmailRequest{
diff --git a/resend.go b/resend.go
index a89f731..0ae999d 100644
--- a/resend.go
+++ b/resend.go
@@ -12,7 +12,7 @@ import (
 )
 
 const (
-	version     = "2.9.0"
+	version     = "2.10.0"
 	userAgent   = "resend-go/" + version
 	contentType = "application/json"
 )