Files with stmi file suffix are related to the data used by Adobe PageMill, a WYSIWYG editor.
STMI file extension - Adobe PageMill data
What is stmi file? How to open stmi files?
File type specification:
The stmi file extension is associated with Adobe PageMill, one of the first WYSIWYG web HTML editors, available for Microsoft Windows and Mac OS systems.
The stmi file contains some kind of data used by Adobe PageMill.
This stmi file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.