Thunderbird no longer shows CSV attachments inline (application/octet-stream) - custom mimeTypes.rdf



Message Reader UI
5 months ago
5 months ago


(Reporter: John Veness, Unassigned)


52 Branch

Firefox Tracking Flags

(Not tracked)



(2 attachments)



5 months ago
User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:53.0) Gecko/20100101 Firefox/53.0
Build ID: 20170518000419

Steps to reproduce:

Receive a message with a CSV attachment.

Actual results:

The CSV was displayed as an attachment which has to be clicked on to view.

Expected results:

The CSV would be displayed underneath the message body.

Comment 1

5 months ago
Please see for more details of this problem - I am "pelago" there. If it is desired for me to copy and paste into this bug report, I'll try to do so.

Comment 2

5 months ago
I've read through the support article and I agree with the supporters.

text/plain can be displayed inline, application/octet-stream usually is not. When I attach a CSV, I get application/, which also doesn't display inline.

I followed the steps in the support ticket, created the message and mimeTypes.rdf and I can confirm that the behaviour has changed from TB 45 to TB 52.

That said, I don't think that manual manipulation of mimeTypes.rdf is supported, and if anything, the behaviour of TB was corrected since application/octet-stream shouldn't have been displayed inline in the first place.

Sadly, we don't have resources to chase the problem, which appears minor and or even undesired behaviour has been fixed.

Comment 3

5 months ago
Created attachment 8870992 [details]

Comment 4

5 months ago
Created attachment 8870993 [details]
test-csv.eml - Test message

Comment 5

5 months ago
Alice, if you have spare time, you could have a look where the behaviour has changed.

Create a new profile. Place mimeTypes.rdf into it. Load the attached message.

In TB 45, the CSV displays inline, in TB 52 is does not. When/where did that change? Perhaps that was done deliberately in M-C.
Flags: needinfo?(alice0775)


5 months ago
Summary: Thunderbird no longer shows CSV attachments inline → Thunderbird no longer shows CSV attachments inline (application/octet-stream) - custom mimeTypes.rdf

Comment 6

5 months ago

To be clear regarding mimeTypes.rdf, I wasn't advocating manually editing it in normal usage. I was just demonstrating it as a minimal cut-down file whichs demonstrates the problem. It was cut down from my own genuine file. There is probably a GUI way to get it into the same state, which is presumably how I got it set like that in older versions of TB.

I understand if application/octet-stream is the "wrong" MIME type that the sending system is using. From my brief research, I've found that that MIME type is relatively common, and when it's used it is normally ignored and the file extension (which in my case is .csv) is looked at instead. That certainly seemed to be the case in v45 and earlier, and ut would be nice for me if that was still the case.

Comment 7

5 months ago
Bad :

Regression window:
Flags: needinfo?(alice0775)

Comment 8

5 months ago
Thanks Alice, as always!

The C-C range shows no relevant changes, the M-C range is sadly empty.
Changing the end date to 14:00 gives

So I'm pretty sure this was change deliberately in bug 306471.

As you might not know, TB is build on Mozilla core software onto which the TB team has no influence. As we stated multiple times, a "nice" and wrong feature has gone away, so nothing we will do about that. Sorry.
Last Resolved: 5 months ago
Resolution: --- → WONTFIX

Comment 9

5 months ago
Thanks. I'm amazed how quickly Alice could narrow down the change which caused this. I can't say I'm entirely happy, but I understand how things work in large projects and I understand. Many thanks for looking into this.
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