Distinguish visible and invisible attachments with Outlook VBA
As I can test so far, an embedded attachment always have a MIME content ID, regardless whether it appears in the mail body. So the solution is to check whether it has a content ID.
Here is an example code that counts the visible attachments:
Sub ShowVisibleAttachmentCount() Const PR_ATTACH_CONTENT_ID As String = "http://schemas.microsoft.com/mapi/proptag/0x3712001F" Const PR_ATTACHMENT_HIDDEN As String = "http://schemas.microsoft.com/mapi/proptag/0x7FFE000B" Dim m As MailItem Dim a As Attachment Dim pa As PropertyAccessor Dim c As Integer Dim cid as String Dim body As String c = 0 Set m = Application.ActiveInspector.CurrentItem body = m.HTMLBody For Each a In m.Attachments Set pa = a.PropertyAccessor cid = pa.GetProperty(PR_ATTACH_CONTENT_ID) If Len(cid) > 0 Then If InStr(body, cid) Then Else 'In case that PR_ATTACHMENT_HIDDEN does not exists, 'an error will occur. We simply ignore this error and 'treat it as false. On Error Resume Next If Not pa.GetProperty(PR_ATTACHMENT_HIDDEN) Then c = c + 1 End If On Error GoTo 0 End If Else c = c + 1 End If Next a MsgBox cEnd SubWhen I run through all my outlook emails it gives the same number of attachments in the line.
UPDATE
Thanks to Dmitry Streblechenko's information, I tested Outlook with email generated by Java Email library. The result shows that when an email attachment contains an CID but not appear in the email body, it will appear in the attachments line.
UPDATE
It looks there are still some cases that this is not good enough.I have generated the following MIME email body:
Message-ID: <1044564324.2.1360638429705.JavaMail.joe@xxxx>Subject: TestMIME-Version: 1.0Content-Type: multipart/alternative; boundary="----=_Part_0_1327112367.1360638429515"Return-Path: xxxx@xxxx.xxxX-OriginalArrivalTime: 12 Feb 2013 03:07:16.0096 (UTC) FILETIME=[0FC1B000:01CE08CE]------=_Part_0_1327112367.1360638429515Content-Type: text/plain; charset=us-asciiContent-Transfer-Encoding: 7bitTTT------=_Part_0_1327112367.1360638429515Content-Type: multipart/related; boundary="----=_Part_1_1747887937.1360638429520"------=_Part_1_1747887937.1360638429520Content-Type: text/html; charset=UTF-8Content-Transfer-Encoding: quoted-printable<html><head><meta http-equiv=3D'content-type' content=3D'text/html; charset==3DUTF-8'></head><title>TTT</title><body><img src=3D"cid:test1.png" alt=3D'==E6=81=AD=E8=B4=BA=E6=96=B0=E7=A6=A7' /><p>txt</p></body></html>------=_Part_1_1747887937.1360638429520Content-Type: image/pngContent-Transfer-Encoding: base64Content-ID: <test.png>iVBORw0KGgoAAAANSUhEUgAAAIIAAAAmCAYAAAAIjkMFAAABHUlEQVR42u3Z0Q7CIAyFYd//pafxckFoS9ELvz8aE9mQrIfTFh8PAAAAAPgp1+t1vT9i32fm6FzP6JrKb3aulRAGARm9Z9dUAhWZY7Wm7Hr+IvhdD+s+PhLCLNBZQZ12HI7QlBqyQohctxM8bvAFIcx2eEYIo/vuY5WAi3BzWlhZ+if7zs7TUWtE10Asgd3bUSxWHvrMobJOtXITQkjk5Z3gdaWaqBBWouYIhdy+E+TsPNHU0CUEbjDJ49GxE0KInBNUheAcYbPVy9QNmRaxUvVHd7Idf0gU2QDOduVqnkinoEb4QY1Q3V2RNrMqpB0h6BqKh0gZIWT/AzjVycwcjSMcPI3buSebZiptaLbIBQAAAAAAAAAAAAAAAP6OJyO5jJ4bZa/gAAAAAElFTkSuQmCC------=_Part_1_1747887937.1360638429520--------=_Part_0_1327112367.1360638429515--Notice that I have changed the referencing image content id in the body, and the actual image have a wrong content ID (so it is not referenced). However the image is not in the main part of the email (it is in a branch of an alternative part). That makes it invisible in outlook.
So to detect we have to make sure the attachment appears in the main MIME part... Looking for ways to do so.
UPDATE
Further digging I reaches this link and I added one more test - the PR_ATTACHMENT_HIDDEN property.
Also it is worth to say that outlook 2010 itself is not consistent. I have observed that sometimes the email list shows the attachment icon to indicate existence of attachments but there are nothing appear when opening it in an inspector.
References:
Some attachments always have the MIME content id (PR_ATTACH_CONTENT_IDenter code here), in particular messages from Lotus Notes always have that header.
The real test is to check the HTMLBody property and see if any attachments are actually referenced by the img tags. Redemption lets you distinguish attachment like that using the RDOAttachment.Hidden property.
Based on answer by @Earth Engine , here it is a function returning the real number of attachments upon passing a mailitem (item.class = olMail) as parameter:
Function CountVisibleAttachment(ByVal m As MailItem) As Integer Const PR_ATTACH_CONTENT_ID As String = "http://schemas.microsoft.com/mapi/proptag/0x3712001F" Const PR_ATTACHMENT_HIDDEN As String = "http://schemas.microsoft.com/mapi/proptag/0x7FFE000B" Dim a As Attachment Dim pa As propertyAccessor Dim c As Integer Dim cid As String Dim body As String c = 0 body = m.HTMLBody For Each a In m.Attachments Set pa = a.propertyAccessor cid = pa.GetProperty(PR_ATTACH_CONTENT_ID) If Len(cid) > 0 Then If InStr(body, cid) Then emb = emb + 1 Else 'In case that PR_ATTACHMENT_HIDDEN does not exists, 'an error will occur. We simply ignore this error and 'treat it as false. On Error Resume Next If Not pa.GetProperty(PR_ATTACHMENT_HIDDEN) Then c = c + 1 End If On Error GoTo 0 End If Else c = c + 1 End If Next a CountVisibleAttachment = cEnd Function