The EX_USAGE error code (value
64) means that a command or configuration line was used incorrectly.
For instance, the sendmail daemon can be
executed only by root, or by the person defined
by the TrustedUser option (TrustedUser). If anyone else tries to run it with
-bd or -bD, the following error
is printed and sendmail exits with an EX_USAGE
error:
Permission denied (real uid not trusted)
Clumsy fingers can also cause problems. If a command-line switch is
used that is unknown to sendmail, the following
error will be printed and sendmail will exit
with an EX_USAGE code:
sendmail: illegal option -- bad option here
When an address is parsed, that address can be rejected if it
contains control characters:
Address contained invalid control characters
If the EightBitMode option (EightBitMode) is specified with a bad character, the
following error is printed and sendmail exits
with an EX_USAGE code:
Unknown 8-bit mode bad character
If the DeliveryMode option (DeliveryMode) is given a bad mode specification with a bad
character, sendmail will print the following
message and exit with an EX_USAGE code:
Unknown delivery mode bad mode here
