E-mails with invalid Content Id

0 votes
asked Jul 22 by 3P (270 points)

In some e-mails that I receive content id's of inline attachments seem to be broken. When I load those e-mails using Rebex classes content id of LinkedResource is empty. Only ContentDisposition.Filename has value. When I look into eml file ContentId is there but it is some number that cannot be found anywhere inside eml - src=3D"cid:16c04ba2d614cff311". When I look at e-mail in Thunderbird I see that inline image is not displayed and in list of attachments I see the file that should be displayed there (with name same as ContentDisposition.Filename). All those e-mails are Re e-mails from gmail.

Is this some known scenario?

Applies to: Rebex Secure Mail

1 Answer

0 votes
answered Jul 22 by Lukas Matyska (55,430 points)

We are not aware of any such issue of Gmail.
Is it possible that the mail was corrupted on the way from Gmail?

Please, compare the raw data of the mail on GMail server and on your mail server.

For GMail, go to Sent items, select the problematic mail, in menu select "Show original".

Gmail menu "Show original"

If you send us the two mails (one from Gmail, second from your mail server) we can analyze it. You can send it to support@rebex.net - please send it in ZIP file to prevent modifications on the way.

commented Jul 25 by 3P (270 points)
I don't have access to original message as it is message sent from client. I'm also a bit hesitant to send you original message. This is part of eml file, you can see there's no Content-Id.

--000000000000e938e1058df2b7f3
Content-Type: image/png; name="image001.png"
Content-Disposition: inline; filename="image001.png"
Content-Transfer-Encoding: base64
Content-ID: <>
X-Attachment-Id:

iVBORw0KGgoAAAANSUhEUgAAAOMAAABNCAYAAABUmNPSAAAAAXNSR0IArs4c6QAAAAlwSFlzAAAO
xAAADsQBlSsOGwAAABl0RVh0U29mdHdhcmUATWljcm9zb2Z0IE9mZmljZX/tNXEAAC9TSURBVHhe
7V0FfNVl277W3cF6jHUxRufoFgTkFQkJ8RUFRFB5FTv4bCxMFAwEDELpkJJGQmIMxsY2Nsa6+yy+
6/6fHZzIqI2FnufH+bHtnPP8n7qfu69bv4oN2qZdAe0KNPoK6Df6CLQD0K6AdgWUFdASo/YgaFeg
iayAlhibyEZoh6FdAS0xas+AdgWayApoibGJbIR2GNoVqJUYVSoV4uPjERkZCX19fXh6eqKivBxl
ZaWoqqrkyuloV6/JroAYyHVQZmyCSj29JjvKOzkwQ847uGVLWJqa3snH1GvftRJjQkICunTpgszM
>>>cut here
--000000000000e938e1058df2b7f3--
commented Jul 25 by Lukas Matyska (55,430 points)
I understand that you hesitate to sent us the mail, but unfortunately in that case, we cannot help you.

Since Content-ID is missing in the eml file, there is no way to correctly link the resource from HTML body.

We wanted to check where the email got corrupted. But, if you have no access to the original Gmail message, you will hardly to diagnose it.

The only reasonable solution how to analyze the issue is to monitor incoming raw data to your mail server and check whether the received mail has Content-ID filled.

I got an idea to probably the simplest solution: ask your customer whether he can see the image correctly in the Sent Mails on his Gmail account.
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