Notes about the SBD file extension:
Incorrect file associations could be the result of underlying issues within your PC system. As such it is highly recommended to scan your PC for invalid registry entries, unused processes and other unfavourable system settings to identify slowdown issues.
The SBD file type is primarily associated with 'Mozilla (Netscape)' by Mozilla.org. Each mail folder (Inbox, Sent, etc.) is stored as two files; one with no extension (e.g. INBOX), which is the mail file itself (in ‘mbox’ format), and one with an .MSF extension (e.g. INBOX.MSF), which is the index (Mail Summary File) to the mail file. There is an optional folder bearing the mailbox name with an SBD extension that contains any sub-folders.