SQL Server

Emails with Related Items that have "Attachment" Content-Disposition

Emails are MIME, and an email with attachments or HTML images are multipart MIME. The MIME parts that are items to be displayed inline within an HTML email are called "related" items. Typically they are images. They are situationed under the "multipart/related" MIME umbrella. Attachments are semantically those files that are attached to an email but typically not displayed inline. They are located under the "multipart/mixed" MIME umbrella.

However, related items and attachments aren't always mutually exclusive. Chilkat considers the semantics of the any individual item, not just the placement within the MIME. Also, many software systems create emails in non-standard ways. There are innumerable ways (going against customary "standards") that multipart MIME can be constructed.

For example, if a MS-Word document is located under a multipart/related, but also the MIME sub-header indicates "attachment", then the MS-Word document would be both a related item and an attachment. This is because some email clients are capable of displaying MS-Word docs inline, but also it's semantically an attachment, because in most cases the MS-Word document is expected to be saved to disk.

Here's a sample MIME sub-header. (You can open .eml files in a text editor to see the MIME headers and sub-headers. If you're not familiar with MIME, ask ChatGPT to explain the basics.)

------=_Part_2795453_726600066.1721122066159
Content-Type: application/octet-stream; name="abcd.docx"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="abcd.docx"

Note: This example requires Chilkat v10.0.0 or greater.

SQL Server

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @iTmp0 int
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

    DECLARE @email int
    EXEC @hr = sp_OACreate 'Chilkat.Email', @email OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    -- Load an email with a MS-Word (docx) MIME part that is considered both a related item and an attachment:
    -- 
    -- ... 
    -- ------=_Part_2795453_726600066.1721122066159
    -- Content-Type: application/octet-stream; name="abcd.docx"
    -- Content-Transfer-Encoding: base64
    -- Content-Disposition: attachment; filename="abcd.docx"
    -- ...
    -- 
    EXEC sp_OAMethod @email, 'LoadEml', @success OUT, 'qa_data/eml/related_item_with_disposition_attachment.eml'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @email, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @email
        RETURN
      END

    -- Examine related items and attachments:

    EXEC sp_OAGetProperty @email, 'NumRelatedItems', @iTmp0 OUT
    PRINT 'Num Related Items: ' + @iTmp0

    EXEC sp_OAGetProperty @email, 'NumAttachments', @iTmp0 OUT
    PRINT 'Num Attachments: ' + @iTmp0

    -- In our example file, we already know it has 1 related item, and 1 attachment,
    -- and they are both the same MS-Word document.
    -- To simplify for the example, we just get the info for the 1st without checking..

    EXEC sp_OAMethod @email, 'GetRelatedFilename', @sTmp0 OUT, 0
    PRINT 'Related filename: ' + @sTmp0

    EXEC sp_OAMethod @email, 'GetAttachmentFilename', @sTmp0 OUT, 0
    PRINT 'Attachment filename: ' + @sTmp0

    -- The filename is "abcd.docx" in both cases.

    -- Get the Content-Disposition header field.
    -- Note: The GetRelatedHeader method is added in Chilkat v10.0.0
    DECLARE @disposition nvarchar(4000)
    EXEC sp_OAMethod @email, 'GetRelatedHeader', @disposition OUT, 0, 'Content-Disposition'
    EXEC sp_OAGetProperty @email, 'LastMethodSuccess', @iTmp0 OUT
    IF @iTmp0 = 0
      BEGIN
        EXEC sp_OAGetProperty @email, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @email
        RETURN
      END

    PRINT 'Content-Disposition: ' + @disposition

    -- Sample output:

    -- Num Related Items: 1
    -- Num Attachments: 1
    -- Related filename: abcd.docx
    -- Attachment filename: abcd.docx
    -- Content-Disposition: attachment; filename="abcd.docx

    EXEC @hr = sp_OADestroy @email


END
GO