Problems to differentiate between attachments and embedded in an email

Question

In my code i have something like that to verify if the attachment is embedded or not:
public static bool IsEmbeddedAttachment(Outlook.Attachment attachment)
//Anexos que não são embedded são obrigatóriamente olByValue, porém os embedded podem ser de qualquer tipo
if (attachment.Type != Outlook.OlAttachmentType.olByValue)
return true;
//Busca a propriedade contentID do anexo. Anexos embedded não precisam necessáriamente gerar um ContentID. Anexos fixos não geram ContentID
string strATTACH_CONTENT_ID = attachment.PropertyAccessor.GetProperty(@"http://schemas.microsoft.com/mapi/proptag/0x3712001E").ToString();
//Busca a propriedade contentLocation. Para que o anexo seja embedded é necessario que essa propriedade esteja vazia ou nulla
string strATTACH_CONTENT_LOCATION = attachment.PropertyAccessor.GetProperty(@"http://schemas.microsoft.com/mapi/proptag/0x3713001E").ToString();
if (!string.IsNullOrWhiteSpace(strATTACH_CONTENT_ID) || !string.IsNullOrWhiteSpace(strATTACH_CONTENT_LOCATION))
//Busca a propriedade AttachFlag se for diferente de 4 é uma imagem embedded
if ((int)attachment.PropertyAccessor.GetProperty(@"http://schemas.microsoft.com/mapi/proptag/0x37140003") == 4)
return true;
if ((int)attachment.PropertyAccessor.GetProperty(@"http://schemas.microsoft.com/mapi/proptag/0x37050003") == 6)
return true;
if ((int)attachment.PropertyAccessor.GetProperty(@"http://schemas.microsoft.com/mapi/proptag/0x37140003") == 4)
return true;
return false;
And was working very well until last week. 
I have a problem with a single email. This email attachments possess 2 PDF type files. These files are not embbed in the email, but they have the contentId property. Could you tell me why? or if its possible discovery why this happens?
PS.: Sorry about my english.

Answer 1

Hi Dmitry,
Thank you again,
Today i have a new issue, An email can have a file of the kind .msg  as attachment. 
when the method is called was made a validation by the Attachment.Type property. But when i have a .msg file this property returns Outlook.OlAttachmentType.olEmbeddeditem. So i changed my code to this:
using Outlook = Microsoft.Office.Interop.Outlook;
public static bool IsEmbeddedAttachment(Outlook.Attachment attachment)
if (!DocumentFormat.IsImageFormat(Path.GetExtension(attachment.FileName)))
return false;
//if is an .msg file is Outlook.OlAttachmentType.olEmbeddeditem
if (attachment.Type != Outlook.OlAttachmentType.olByValue)
return true;
//Busca a propriedade contentID do anexo. Anexos embedded não precisam necessáriamente gerar um ContentID. Anexos fixos não geram ContentID
string strATTACH_CONTENT_ID = attachment.PropertyAccessor.GetProperty(@"http://schemas.microsoft.com/mapi/proptag/0x3712001E").ToString();
//Busca a propriedade contentLocation. Para que o anexo seja embedded é necessario que essa propriedade esteja vazia ou nulla
string strATTACH_CONTENT_LOCATION = attachment.PropertyAccessor.GetProperty(@"http://schemas.microsoft.com/mapi/proptag/0x3713001E").ToString();
if (!string.IsNullOrWhiteSpace(strATTACH_CONTENT_ID) || !string.IsNullOrWhiteSpace(strATTACH_CONTENT_LOCATION))
return true;
if ((int)attachment.PropertyAccessor.GetProperty(@"http://schemas.microsoft.com/mapi/proptag/0x37050003") == 6)
return true;
if ((int)attachment.PropertyAccessor.GetProperty(@"http://schemas.microsoft.com/mapi/proptag/0x37140003") == 4)
return true;
return false;
but i still have a problem, i cant get the attachments from THIS attachment(the .msg file) and i need to get these attachments. How can i get this attachments?
ps.: Sorry about my english.
att,s
Rissardi