The Resend function converts SENT emails to UNSENT emails by changing the X-Unsent email header of  an .eml file from X-Unsent: 1 (sent)  to X-Unsent: 0 (not sent). The email will be then be opened in Compose Email Mode when you open the file in Outlook Express. This is handy to use for email message templates.

The Outlook Express April Security update KB911567 removes the feature that allows you to save unsent messages for use as message templates. The Resend button will not work and the .eml file will be opened in sent mode. You have to install the new update KB918766 to fix this. After installing you will have to edit the registry before you can use saved *.eml files as message templates. To do so:

1. Close Outlook Express and any open message or address book window.

2. Go to Windows Update and (re-)install KB911567.

3. Go to the Windows Download Center, download and install KB918766.

4. Open Regedit and navigate to this key:

5. On the Edit menu, point to New, then click Key and copy/paste this name exactly as shown:

FEATURE_HONOR_XUNSENT_IN_FILE

6. On the Edit menu, point to New, then click DWORD Value and name it msimn.exe.

7. Double-click msimn.exe and change the value to 1.

To make this registry change (steps 4 to 7) easier, you can install the supplied small registry file

feature_honor_xunsent_in_file.reg

Just right click on the file and select Merge.