I am working on a strange problem today. One user complained that he cannot send any pdf document properly through Thunderbird. The user could send other attachments alright, but whenever he tried to send a PDF as attachment, the attachment would be treated as XHTML.
I tried to send the same PDF from another account, and that was fine. I then knew that the problem is not Thunderbird itself. The problem is the individual’s account settings. From my experience, it’s usually caused by MIME not set correctly. I looked through the GUI interface thoroughly. However, I couldn’t find any dialog to set the MIMI types. Looking through the profile folder, I found a file called mimeTypes.rdf. The mimeTypes.rdf file for the problematic account is bigger than the same file for an account that is working. At first, I tried to find out what are the differences between the files. But then it stuck me that I could just use the mimeTypes.rdf that’s working correctly. So, I copied the good mimeTypes.rdf over the bad mimeTypes.rdf. Thunderbird can send PDF attachments correctly afterward.
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