I have an Outlook VSTO add-in and I need to determine if the Outlook.MailItem being processed corresponds to a saved file on the local disk that has been opened in Outlook, regardless of the type of account configured (Exchange, IMAP, etc.). I need to differentiate it from a draft or any other type of email in any folder which is not a saved email.

Specifically, I need to detect unequivocally whether a MailItem was saved on the local disk and then opened in Outlook so that I can perform certain actions.

Here is a combination of things I have tried without success:

• Checking the Explorer count
• Checking the MailItem.EntryID
• MailItem.ConversationID
• MailItem.StoreID
• Retrieving the MailItem based on its ID and then performing the actions only for a locally saved file

However, my logic is being executed for other selected emails in the inbox, drafts, etc., not just for locally saved files.

Below is the code snippet I have tried:

public bool IsLocalFile(Outlook.MailItem mailItem)
{
    if (string.IsNullOrEmpty(mailItem.EntryID) && string.IsNullOrEmpty(mailItem.StoreID))
    {
        return true;
    }
    return false;
}

public string GetLocalFilePath(Outlook.MailItem mailItem)
{
    Outlook.PropertyAccessor propertyAccessor = mailItem.PropertyAccessor;
    try
    {
        return propertyAccessor.GetProperty("http://schemas.microsoft.com/mapi/proptag/0x7D01001E") as string;
    }
    catch (System.Exception ex)
    {
        return null;
    }
}

        public bool IsInFolder(Outlook.MailItem mailItem)
        {
            Outlook.MAPIFolder parentFolder = null;
            try
            {
                parentFolder = mailItem.Parent as Outlook.MAPIFolder;
                return parentFolder == null;
            }
            catch
            {
            }

            return false;
        }

        public bool IsSaved(Outlook.MailItem mailItem)
        {
            Outlook.MAPIFolder parentFolder = mailItem.Parent as Outlook.MAPIFolder;
            if (parentFolder!=null)
            {
                string folderPath = parentFolder.FolderPath;
                if (folderPath=="C:\EmlFolder"||folderPath=="C:\Attachments")
                {
                    return true;
                }
            }

            string messageContent = mailItem.Body;
            if (messageContent.Contains("Content-Type: multipart/related")||mailItem.BodyFormat==Outlook.OlBodyFormat.olFormatHTML)
            {
                return true;
            }

            if (mailItem.InternetCodepage==0)
            {
                return true;
            }

            return false;
        }

        public string GetLocalFilePath2(Outlook.MailItem mailItem)
        {
            if (!string.IsNullOrEmpty(mailItem.EntryID)&&string.IsNullOrEmpty(mailItem.StoreID))
            {
                Outlook.NameSpace outlookNamespace = mailItem.Session.Application.GetNamespace("MAPI");
                Outlook.MailItem copiedMail = outlookNamespace.GetItemFromID(mailItem.EntryID);

                if (copiedMail!=null&&!string.IsNullOrEmpty(copiedMail.PropertyAccessor.GetProperty("http://schemas.microsoft.com/mapi/proptag/0x370E001F")))
                {
                    return copiedMail.PropertyAccessor.GetProperty("http://schemas.microsoft.com/mapi/proptag/0x370E001F") as string;
                }
            }

            return null;
        }

Then I check all above in a conditional:

if (mailItem.Session.Application.Explorers.Count == 0 ||
    (string.IsNullOrWhiteSpace(mailItem.ConversationID) && !mailItem.IsDraft()) ||
    IsLocalFile(mailItem) ||
    !string.IsNullOrWhiteSpace(GetLocalFilePath(mailItem)) ||
    !IsInFolder(mailItem) ||
    IsSave(mailItem) ||
    !string.IsNullOrWhiteSpace(GetLocalFilePath2(mailItem)))
{
   // do stuff only in case it is a saved mail in local disk
}

Can anyone provide a reliable method to detect if a MailItem is a locally saved file opened in Outlook? I will highty appreciate it. Thanks in advance.