Beginning with V8.7, sendmail looks for its datafile (the file containing the message body) under the same name as its qf file, but with the q changed into a d. Prior to V8.7, the D line in the qf file contained the name of the file that contained the message body. If the D line was missing, there was no message body. The form of the qf file D line was:

Dfile

The D must begin the line. The file must immediately follow with no intervening space. All text, from the first character following the D to the end of the line, is taken as the name of the file. There is no default for file; either it must be present, or the entire D line must be absent.

The sendmail program opens the df file for reading. If that open fails, sendmail syslog(3)s the following error message at LOG_CRIT and continues to process the qf file:

readqf: cannot open dfAA12345

Be aware that sendmail attempts to remove the file after it has been delivered to all recipients. If sendmail is unable to remove the file, and if the LogLevel option (LogLevel) is greater than 97, sendmail syslog(3)s the following warning at LOG_DEBUG:

file: unlink-fail #

The file is the name of the file that could not be removed. The # is the error number, as defined in /usr/include/errno.h.

The df file is opened only when processing the queue file, not when printing it. When printing the queue, the df is stated so that its size can be printed.