Check your settings on: options / attachments / incoming that HTML-document are set to Firefox

HTMLL-document does not show up in options/attachments/incoming

Do you have anything there?

Yes. Several content types. e.g. Adobe Acrobat, doc file, docx file, ics file, JPEG, MPEG-4, XLS.

I don't see a process for adding file types and the default action.

Probably your MimeTypes.rdf (in your profile-directory) is corrupt Renaming or move it somewhere Then start TB If you dubbel - click on a link, a question about what to do pops up. There is a choice to do this always.

Now if you look at options/attachments/incoming you should have one entry. Problem is you have to do this for every attached type.

You could try this before you rename/move mimeTypes.rdf Or you might (if your skilled enough) edit that file.

Okay, I believe you have crossed over into my level of incompetency. I cannot find my MimeType.rdf file (Profile Directory). And I don't know what TB stands for. Sorry.

If you can give me the steps, I believe I can follow.

TB = ThunderBird Open help/Troubleshooting information click on "Show Folder" CLOSE TB Now you should find MimeTypes.rdf

But first try double-click on a html - link (with Firefox NOT started) If you get a popup like this check to do it always