Is there anyone who could steer me in the right direction as to how to add a mime type that is not included in the default Thunderbird installation?

Marc

When I get .odt attachments in my emails, I do not get an option to "Open" the file, or to "Choose which application to use" to open the file.

What actually happens when you attempt to open an .odt attachment from a received message?

If I right-click on the attachment it gives me the option to "open" but does not give me the option "Choose which application". It would be nice if this were part of the attachment process where if a new mime-type were attached, the user could assign a software package to open the mime-type.

But, then again, considering that the opendocument users worldwide are used by the hundreds of millions, one would think that Thunderbird would add these as default along with the other default proprietary mime-types.

If I right-click on the attachment it gives me the option to "open" but does not give me the option "Choose which application".

What happens when you click "Open"?

considering that the opendocument users worldwide are used by the hundreds of millions

How do you know it's that many?

The mimetype is encoded at the time the email is "compiled" not when it is received.

Then we have the more special issue. There are no "mimetypes" for .odt, .ods, .odp, .odg

Open document formats are described by the IETF here https://www.iana.org/assignments/media-types/media-types.xhtml

I suggest you search the page (ctrl+F) for openxmlformats just to get an idea of how many formats are involved.

Now open the message source and look for the attachment.

This is an example;

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

While this is clearly a docx file to you and me it is described in the Content-Type as application/octet-stream

So this file will not be recognized by Thunderbird as anything but a binary data-stream because it is explicitly encoded as such. So it will be tossed to the operating system in the hope it has some idea what to do with it. If not, save will be the option offered. Word files are actually encoded the same way as LibreOffice files as they are both open document formatted files. In the case of a DOCX document file as vnd.openxmlformats-officedocument.wordprocessingml.document

This is another real world example Content-Type: text/rtf; charset=UTF-8; name="Off.rtf" Content-Disposition: attachment; filename="Off.rtf"

This will be passed to the RTF file handler set up in Thunderbird without reference to the operating system because the file is correctly encoded by the sender.

What is perhaps the saddest part of the whole thing about email attachments is the volume of incorrectly encoded media types. However over the years I have observed in developer forums that Windows developers really just do not appear to comprehend what the media type is for. It is used extensively in the internet, email and on Linux, Unix and Mac machines file handlers. But the majority of windows developers leave comments on forums like "I use Application/Octet stream because it works, I do not know what it means."

If I right-click on the attachment it gives me the option to "open" but does not give me the option "Choose which application".

What happens when you click "Open"?

Nothing happens, no other option is offered. The menu disappears.

considering that the opendocument users worldwide are used by the hundreds of millions

How do you know it's that many?

I am part of the LibreOffice marketing team since the beginning and that is the number of active users estimated by The Document Foundation. It is also publicly stated on Wikipedia which is kept updated by the TDF.

Hi Matt,

If I understand you correctly, then the open document format(s) have not created appropriate mime-types and this is the problem?

Marc