/* If set, missing messages are stored in ghost mail documents.
* If unset, thread IDs of ghost messages are stored as database
* metadata instead of in ghost documents.
*
* Introduced: version 3. */
/* If set, missing messages are stored in ghost mail documents.
* If unset, thread IDs of ghost messages are stored as database
* metadata instead of in ghost documents.
*
* Introduced: version 3. */