如何在outlook vba中分配已发送邮件的类别？

Sub CategorizeSentEmails()
    Dim objNamespace As Outlook.Namespace
    Dim objSentFolder As Outlook.Folder
    Dim objSentItems As Outlook.Items
    Dim objMail As Outlook.MailItem
    
    ' 获取Outlook应用程序的命名空间
    Set objNamespace = Application.GetNamespace("MAPI")
    
    ' 获取已发送邮件夹
    Set objSentFolder = objNamespace.GetDefaultFolder(olFolderSentMail)
    
    ' 获取已发送邮件夹中的所有邮件
    Set objSentItems = objSentFolder.Items
    
    ' 遍历已发送邮件夹中的每封邮件
    For Each objMail In objSentItems
        ' 检查邮件是否为MailItem类型
        If TypeOf objMail Is Outlook.MailItem Then
            ' 分配类别
            objMail.Categories = "MyCategory"
            ' 保存更改
            objMail.Save
        End If
    Next objMail
    
    ' 释放对象
    Set objMail = Nothing
    Set objSentItems = Nothing
    Set objSentFolder = Nothing
    Set objNamespace = Nothing
End Sub