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On Jun 23, 2008, at 10:49 PM, Alec Warner wrote: > On Wed, Jun 4, 2008 at 1:02 PM, Tom Rockwell <[log in to unmask]> > wrote: >> Is there a easy and fast way for a user to probe what mail >> addresses are >> available? So far I've used the method of asking the help desk >> about a >> single email address, this was not hard to do, but took a few hours >> for a >> response (which was negative). I see a scaling issue... > > Define 'easy'. > > Originally the SMTP protocol had an 'expn' feature; however due to > spammers using it to harvest active email addresses it has since been > disabled in most environments. > > -bash-2.05b$ telnet lb.mail.msu.edu 25 > Trying 35.9.75.15... > Connected to lb.mail.msu.edu (35.9.75.15). > Escape character is '^]'. > 220 mx06.mail.msu.edu ESMTP Exim 4.63 Mon, 23 Jun 2008 22:39:48 -0400 > expn [log in to unmask] > 550 Administrative prohibition > ^] > > telnet> Connection closed. > > You could of course do something like: > > antarus@woodpecker ~ $ telnet lb.mail.msu.edu 25 > Trying 35.9.75.15... > Connected to lb.mail.msu.edu. > Escape character is '^]'. > 220 mx04.mail.msu.edu ESMTP Exim 4.63 Mon, 23 Jun 2008 22:42:33 -0400 > ehlo smtp.gentoo.org > 250-mx04.mail.msu.edu Hello smtp.gentoo.org [140.211.166.183] > 250-SIZE 52428800 > 250-PIPELINING > 250 HELP > mail from: [log in to unmask] > 250 OK > rcpt to: [log in to unmask] > 250 Accepted > ^] > telnet> Connection closed. > > hurrah; it accepted mail; ergo that address is in use. > > 220 mx00.mail.msu.edu ESMTP Exim 4.63 Mon, 23 Jun 2008 22:44:35 -0400 > ehlo smtp.gentoo.org > 250-mx00.mail.msu.edu Hello smtp.gentoo.org [140.211.166.183] > 250-SIZE 52428800 > 250-PIPELINING > 250 HELP > mail from: [log in to unmask] > 250 OK > rcpt to: [log in to unmask] > 550 5.1.1 unknown user [log in to unmask] > > and as expected it doesn't accept email for my made up fake address. > > The RCPT TO is of course not very nice to the msu mail servers as I'm > sure they have better things to do like send and receive email; so I > would be careful in using it. Maybe I wasn't clear enough about this the first time: Just because an account appears to not exist in mail doesn't mean the netid is available. ./mk -- Matt Kolb <[log in to unmask]> Assistant Director Academic Technology Services Michigan State University