I get the following error
Failed to create COM object `hMailServer.Application': Access is denied.
This problem is often caused by DCOM permissions not being set.
I tried almost all the suggestions about enabling php dcoms and giving dcom permission. In fact, I have given "Everyone" permissions.
My server is running on Windows IIS 8, with Parallels Plesk installed. PHP 5.5, hMailserver 5.x, Mod Security Enabled.