Normally, IMail Server cleans up the .tmp and attached files as part of the delivery process. However, if there is an SMTP failure during delivery, these files may not be deleted. You can also run the Spool Cleaner utility (isplcln.exe) to delete old files.
A damaged or corrupt file in the queue can prevent mail from being received correctly. If you suspect that this is the cause of a problem you have, you can try moving all files from the Spool directory to a temporary location (such as IMAIL\SPOOL\SAVE) and then see if you can receive mail. If you can receive mail, copy back pairs of files to the Spool directory and see if they get sent. Messages that are not sent may be damaged or corrupt files.
Related Topics
About the Spool Directory (Queue)