Marcel Montes: > What does postfix actually add to the bounce message? > The STDERR output if the return status is not 0?
Postfix absorbs stdout and stderr. There is some information in the pipe(8) man page, but it is not complete. Wietse DIAGNOSTICS Command exit status codes are expected to follow the conventions defined in <sysexits.h>. Exit status 0 means normal successful comple- tion. Postfix version 2.3 and later support RFC 3463-style enhanced status codes. If a command terminates with a non-zero exit status, and the command output begins with an enhanced status code, this status code takes precedence over the non-zero exit status. Problems and transactions are logged to syslogd(8). Corrupted message files are marked so that the queue manager can move them to the corrupt queue for further inspection.