An exit value of EX_IOERR (the value 74) means that a serious operating system error occurred. This class of error relates mostly to disk I/O.

If the body of a mail message could not be read, the following error message is logged:

putbody: dir/dfqid: read error

The file might have vanished because of a disk crash and might have been restored to lost+found. The dir is the queue directory, and the qid is the queue identifier that will help you to find the qf file. Inside that qf file is an I line that gives the inode and major and minor device numbers of the disk that held the df file (I line).

An error that occurs while writing to the pipe(2) connection to a delivery agent causes the following error to be logged and the fork(2)'d child to exit with EX_CONFIG:

putbody: write error