sendmail, 4th Edition

Ordinarily, V8 sendmail sends notification of failed mail to the envelope sender. It specifically does not send notification to the addresses listed in the Errors-To: header. It does this because the Errors-To: header violates RFC1123. For additional information about the Errors-To: header, see Errors-To:.

The UseErrorsTo option is available to prevent older versions of mail-reading software from failing. When set, it allows error notification to be sent to the address listed in the Errors-To: header in addition to that sent to the envelope sender.

The forms of the UseErrorsTo option are as follows :

O UseErrorsTo= bool configuration file (V8.7 and later) -OUseErrorsTo= bool command line (V8.7 and later) define(`confUSE_ERRORS_TO', bool) mc configuration (V8.7 and later) Ol bool configuration file (deprecated) -ol bool command line (deprecated)

The optional argument bool , when missing, defaults to true (errors are sent to the Errors-To: header). If this option is missing entirely, it defaults to false (the Errors-To: header is ignored).

The UseErrorsTo option is not safe. If specified from the command line, it can cause sendmail to relinquish its special privileges.