ICS Default Glitch
Every time I click on an ICS file, it asks me what to do with it. I tell it to open with Thunderbird, and I check the box for it to do that by default. But it doesn't remember, so I have to select Thunderbird from the list every time. Thunderbird is set as the default in the Options>Applications menu, but it still asks every time.
An automatic action will only work properly if the server sends the ICS file with a valid content (MIME) type. If that isn't the case and a generic content type like "application/octet-stream" or a content-disposition:attachment header is send then this won't work.
I posted a sample .ics file on my server. The file is served as
with no special disposition instructions:
Does your Firefox handle it automatically as desired?
Assuming so, there is nothing wrong with your Firefox configuration, the problem is that the server either sets the Content-Type wrong or sets Content-Disposition: attachment.