Outlook EWS：保存EML时是否将userproperties添加到EML？

在我的一些邮件中，我通过Outlook存储了一些用户属性

item.UserProperties.Add("CustID", Outlook.OlUserPropertyType.olText)
item.UserProperties("CustID").Value = custID.ToString

在未安装Outlook的Pc（服务器）上，我想以EML形式下载邮件并存储用户属性（如“CustID”等）

我的EML保存代码：

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    Dim service As New ExchangeService(ExchangeVersion.Exchange2013)
    service.Credentials = New WebCredentials("my@email.com", "mypsw")
    service.Url = New System.Uri("https://outlook.office365.com/EWS/Exchange.asmx")

    Dim entryID As String = "00000000C802F40668D27342B788D508E9210A67005DF9A7DEF7194A418C8515031D4262280000E00005DF9A7DEF7194A418C8515031D4262280002A9D18B320000"
    Dim id As New ItemId(Convert(service, "my@email.com", entryID))
    Dim email As EmailMessage = EmailMessage.Bind(service, id)

    Dim ps As PropertySet = New PropertySet(ItemSchema.MimeContent)
    email.Load(ps)

    Using fileStream = New IO.FileStream("D:\sandbox\_email_test.eml", IO.FileMode.Create)
        fileStream.Write(email.MimeContent.Content, 0, email.MimeContent.Content.Length)
    End Using
End Sub


Private Function Convert(service As ExchangeService, mailbox As String, entryID As String) As String
    Dim originalID As New AlternateId()
    originalID.Format = IdFormat.HexEntryId
    originalID.Mailbox = mailbox
    originalID.UniqueId = entryID 'EntryId retrieved from email in Outlook
    Dim altBase As AlternateIdBase = service.ConvertId(originalID, IdFormat.EwsId)
    Dim convertedID As AlternateId = DirectCast(altBase, AlternateId)
    Dim strConvertedID As String = convertedID.UniqueId
    Return strConvertedID
End Function

有没有办法在EML中存储userproperties？如果是，如果我双击EML在Outlook中打开它，我可以从EML读回userproperties吗

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谢谢

用户属性是Mapi/扩展属性，不包括在消息的模拟流中。如果您将属性添加为X-Header，则它们将在MimeSteam中可用，否则您最好将消息导出为MSG文件，这将为您提供所有MAPI属性的完全保真度。要将其导出为MSG，您需要使用Outlook，如果需要自动化，还可以查看类似于redemption的内容

干杯 峡谷