The new spool fs tree format has been designed to enable AfterLogic XMail Server to handle very large queues. Instead of having a single spool directory (like versions older than 0.61) a two layer deep splitting has been introduced so that its structure is:
0 <dir> 0 <dir> mess <dir> rsnd <dir> info <dir> temp <dir> slog <dir> cust <dir> froz <dir> ... ...
When AfterLogic XMail Server needs to create a new spool file a spool path is chosen in a random way and a new file with the format:
mstime.tid.seq.hostname
is created inside the 'temp' subdirectory. When the spool file is ready to be committed, it's moved into the 'mess' subdirectory that holds newer spool files. If AfterLogic XMail Server fails sending a new message (the ones in mess subdirectory) it creates a log file (with the same name of the message file) inside the 'slog' subdirectory and move the file from 'mess' to 'rsnd'. During the message sending the message itself is locked by creating a file inside the 'lock' subdirectory (with the same name of the message file). If the message has permanent delivery errors or is expired and if the option 'RemoveSpoolErrors' of the 'SERVER.TAB' file is off, the message file is moved into the 'froz' subdirectory.