+For backward compatibility,
+.B sendmail/smtp
+can be abbreviated to
+.BR sendmail .
+.PP
+The third alternative,
+.BR sendmail/pipe ,
+also forks a local copy of
+.B sendmail
+but feeds the message directly to it, using
+.B sendmail
+.BR -t .
+This replaces the old, undocumented
+.B spost
+mechanism and retains some of its limitations, such as lack of
+support for the
+.B \-whom
+switch and
+\*(lqDcc:\*(rq header field.