An schd file extension is related to the Microsoft Email software. An schd file contains schedule.
SCHD file extension - Microsoft Email schedule
What is schd file? How to open schd files?
File type specification:
The schd file extension is associated with some older email software by Microsoft for Macintosh computers.
Most likely some old format without support from developer. No further information could be found.
This schd 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.