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