murray@motto.UUCP (Murray S. Kucherawy) (04/23/91)
What does it mean when a rewrite rule returns nothing? Will it produce an error in actual use, or will sendmail timeout, or will it try again... what happens? =============================== Murray S. Kucherawy ========================== Motorola Canada, Ltd. Communications Division, Toronto [on work term] University of Waterloo, Ontario, Canada 2B Math/Computer Science Internet: murray@motto.UUCP (work) mskucherawy@watmath.UWaterloo.ca (UW) UUCP: uunet!utai!lsuc!motto!murray uunet!watmath!mskucherawy
rickert@mp.cs.niu.edu (Neil Rickert) (04/24/91)
In article <78@motto.UUCP> murray@motto.UUCP (Murray S. Kucherawy) writes: >What does it mean when a rewrite rule returns nothing? Will it produce >an error in actual use, or will sendmail timeout, or will it try again... >what happens? What exactly do you mean by 'returns nothing'? If the rewrite ruleset does not return, you probably have in infinite loop going which is burning up CPU cycles. If it does return, it returns something, possible the null string. It is permissible for a rewrite rule to return the null string. You may occasionally see SMTP mail where the envelope sender (the MAIL-From SMTP command) lists a sender address of <> . This is accomplished by returning a null address from sender rewrite rule, as perhaps in: R@ $@ Something like this shows up in some versions of sendmail.cf, where an incoming address <> is converted to just @, then later converted back if the sending mailer uses SMTP. However you should be very careful to never output null addresses except for the SMTP envelope sender. Just imagine what will happen to the Unix 'From ' line on say UUCP mail, if you did that there. Many rulesets prefer to replace null addresses with either Postmaster or with MAILER-DAEMON. -- =*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*= Neil W. Rickert, Computer Science <rickert@cs.niu.edu> Northern Illinois Univ. DeKalb, IL 60115 +1-815-753-6940