Disclaimer: I have never successfully configured the password plugin to work with hmail on Roundcube.
My system:
Windows 2008 R2 Standard
hMailServer 5.4-B1950
Roundcube 0.9.5
PHP 5.5.7 non thread safe
I have enabled dcom in php.ini. I have added the IUSR account to the DCOM properties of hMailServer. I have modified the password config.inc.php to use hmail, remote server=false, server=localhost. In Roundcube web interface I see the password option in Settings, but when I enter a new password it just shows the standard "The website cannot display the page" message with the URL:
http://serveraddress/?_task=settings&_action=plugin.password-savePreviously with PHP 5.3 and Roundcube 0.9.2. It would display an error message on the password page (can't remember what it said).
Any ideas?
EDIT: RESOLVEDWith PHP 5.5.7 in the php.ini file you need to both:
Uncomment the line: com.allow_dcom = true
Add the line: extension=php_com_dotnet.dll
In the DCOM Config properties for hMailServer, add IIS_IUSRS to Launch and Activation Permissions with local allow access (I also added it to Access Permissions and Configuration Permissions, but I don't think those are necessary)
After making these changes, the password plugin works as expected!