sendmail, 4th Edition

The stab database-map type is used internally by sendmail to load the raw aliases (5) file into its internal symbol table. ^[16] This is a fallback position that is taken if no database form of aliasing is found.

^[16] As such, it is somewhat misnamed. One might reasonably expect a type named stab to provide access to the symbol table, but alas, this is not so.

The stab type should never be used in configuration files.