.MBG File Extension

Archived mailbox created by Mailbag Assistant, a tool for organizing, analyzing and archiving e-mails; saves messages in a compressed format to save disk space.

MBG files can also be read by Fookes Software Aid4Mail.

File used by Microsoft Mail, a mail server program, for organizing mail messages; contains mail headers that point to the actual mail (.MAI) files; often compressed using the Compress Mailbag utility included with Microsoft Mail.