Start here:

1. View -> Message Body as -> Original HTML
2. View -> Display Attachments Inline (check it)
3. Preferences -> Attachments -> Incoming - see if the file type you are trying to open is listed. Make entries and assign an action or select "Always Ask"

Many thanks for your response Duggabe. Unfortunately, it doesn't solve my problem. While I can tell Thunderbird, for example, to use Word to open a text document and to remember this action, it will still not open an attachment, or remember it for the next time. I have to first save the document and then open it in the normal way. I confirm I am viewing messages in Original HTML and displaying attachments inline.

Any further advice will be appreciated.

Is the problem only with Word documents, or do other types (such as plain text, email, etc) not work either?

Do you see the content of the inline attachments?

Duggabe - firstly, thank you for your interest.

As it stands at the moment I can open pdfs. Adob Reader is shown as the default application for this under Tools>Options>Attachments. Other attachments, Word or Excel for example, will not open within Thunderbird, although I can save them and then open them. When I double click on them I am given the option to specify what application I want to use to open them. If I then choose Word or Excel, and then set it as the default application, nothing happens. Neither do they then appear as the default application under Tools as above.

Inline attachments, typically jpgs, are visible, but will not open if I specify Windows Photo Viewer or Paint as the default application.

Any further help would be much appreciated.

• Do you have any anti-virus software running? If so, try running with it disabled.
• Try running without add-ons. Help -> Restart with add-ons disabled.

Beyond that, someone else may be able to shed some light on it. As a matter of fact, my wife's Win 8.1 has the same problem with Word and Excel, but she rarely receives such attachments. :)

I'm running Avast anti-virus software and had already tried disabling this and also running Thunderbird in safe mode. I've tried both these again, but still have the same problem. Many thanks for your input, and it's good to know I'm not the only person experiencing this problem!

Viscountfan said

I'm running Avast anti-virus software and had already tried disabling this and also running Thunderbird in safe mode. I've tried both these again, but still have the same problem. Many thanks for your input, and it's good to know I'm not the only person experiencing this problem!

Same problem, same config: Win8.1 + Avast Therefore I'd think Avast Antivirus is the clue but how to solve the problem?

The attachment opening problem was solved just now with updating Thunderbird to 38.0.1 ! All kinds of attachment can be opened now