An exit value of EX_CANTCREAT (the value 73) means that an output file could not be written to. This error generally refers to a user-specified file rather than a system- or configuration-file-specified file. For example, an attempt to write to a file that has any execute bit set in its permissions can yield an error, as can a file that has more than one link, and (if the SafeFileEnvironment option, SafeFileEnvironment, is set) a file that is not a regular file. Note that some problems can lead to this error, without printing an error message.

If the SafeFileEnvironment option is specified and sendmail is unable to chroot(2) into the specified directory, the following message is logged:

mailfile: Cannot chroot(directory)

When delivery is to a file, sendmail will log the following error if the file cannot be opened or stat(3)'d, and the fork(2)'d child will exit with EX_CANTCREAT:

cannot open: reason here
cannot fstat: reason here