EWS管理api：有没有办法确定电子邮件或附件是否加密？

Question

EWS托管API是否公开任何属性以识别项目（电子邮件/附件）是否已加密？

Answer 1

 var isEmailOpaqueSignedOrEncrypted = false;

if (email.ItemClass == "IPM.Note.SMIME")
{
    var attList = email.Attachments.ToList();
    if (attList.Count == 1)
    {
        isEmailOpaqueSignedOrEncrypted = true;
    }
};