修改sendmail.cf
        修改sendmail.cf的基本步聚如下：
        (1) 增加新的Mailer: bbsmail
                用vi打开/etc/sendmail.cf，查找下面的语句(段落)
                ##################################################
                ###   Local and Program Mailer specification   ###
                ##################################################
                在这个注释段下面已有两个Mailer的定义，就是local和prog：
                Mlocal,     P=/bin/mail, F=lsDFMAw5:/|@qSnE9,
                              S=10/30, R=20/40,T=DNS/RFC822/X-Unix,
                              A=mail -f $g -d $u
                Mprog,      P=/bin/sh, F=lsDFMoqeu9,
                              S=10/30, R=20/40, D=$z:/,T=X-Unix,
                              A=sh -c $u
                在其后加入：
                Mbbsmail,P=/export/home/bbs/bin/bbsmail,F=lsSDFMuhP,S=10,
                           R=20A=bbsmail -d $u $s
                注意：/export/home/bbs请换成你自己的BBS的所有目录，
                      如home/bbs
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