Open .eml files in compose mode in outlook 2010

Question

I want my users to be able to open eml files in compose mode in outlook 2010, by default it opens in readonly mode. Is there any way out?

Use: We generate email templates which the users can download and customize it before sending.

Answer 1

If you can add the header "X-Unsent: 1" to your .eml, it should open in Compose mode.

Answer 2

Works on Microsoft Outlook but does not work on thunderbird.

A related discussion can be found here https://bugzilla.mozilla.org/show_bug.cgi?id=688284

Answer 3

Mail on MacOS adds this header internally:

X-Uniform-Type-Identifier: com.apple.mail-draft

Unfortunately, this will still not allow you to sent it directly. However, you can move any mail to your drafts folder and then sent it from there.