So I advise my 'illiterate' family/colleagues to NEVER open an emailed attachment unless it can be opened directly in Thunderbird.. - but this requires ALL 'safe' attachments to be 'pre-selected' in Thunderbird's list..

Thunderbird is very security conscious in that it will not simply run an attachment with a 'known' extension unless it has been specifically selected in Thunderbird's 'list'.. This is a great feature for computer-illiterates who tend to click on all (potentially dangerous) attachments without a second thought! So I advise my 'illiterate' family/colleagues to NEVER open an emailed attachment unless it can be opened directly in Thunderbird.. - but this requires ALL 'safe' attachments to be 'pre-selected' in Thunderbird's list.. Striata Reader is used by a number of banks to send secure, encrypted, password-protected statements. I would very much like to add its *.emc extension to Thunderbird's list, ... but... - It's 'weird' installation regime (presumably to make it less prone to virus attack) of installing a *.dll file instead of a regular *.exe, and using rundll32.exe with parameters to execute itself, makes it impossible to select it directly within Thunderbird. So this requires the attachment to be saved and executed outside of Thunderbird - something I definitely don't want my 'illiterates' to get into the habit of doing!! While its clearly possible to write a small 'wrapper' app to execute rundll32 with the correct parameters and add that to the list instead, I'm hoping you may have a simpler solution for me..?