On Fri, 2004-02-06 at 14:57, Rudolf A. A. wrote: > Hello, > > I have a question about sendmail and mail in general. > > I want to know is it possible to know if there are some specific users > in some specific servers. > for example On mydomain.com I have user myuser@xxxxxxxxxxxx, and > people from outside want to know if this user exists or not ?, so how > can they do that ?. I mean to know this, without sending email. > Otherwise they can send email, and if the mail does not come back, It > means the user exists :). > Or without sending email to him, how can I know, is there a such user > ivantan@xxxxxxxxxxx ?. > > Thanks in advance. > Rudolf. > Although the method below may not work on some systems (Ed's example for instance) it will work on most... Telnet the receiving MTA, begin the start of the SMTP protocol and quit before sending the mail. For example... <response for a VALID mailbox> telnet mta 25 Trying 192.168.0.1... Connected to mta. Escape character is '^]'. 220 ESMTP Sendmail 8.12.8/8.12.8; Fri, 6 Feb 2004 22:03:59 GMT helo beast 250 Hello beast [192.168.0.2], pleased to meet you mail from: <some.user@xxxxxxxxxxx> 250 2.1.0 <some.user@xxxxxxxxxxx>... Sender ok rcpt to: <valid.user@xxxxxxxxxxxxxx> 250 2.1.5 <valid.user@xxxxxxxxxxxxxx>... Recipient ok quit 221 2.0.0 closing connection Connection closed by foreign host. <response for a INVALID mailbox> [saultj@beast saultj]$ telnet mta 25 Trying 192.168.0.1... Connected to mta. Escape character is '^]'. 220 ESMTP Sendmail 8.12.8/8.12.8; Fri, 6 Feb 2004 22:07:02 GMT helo beast 250 Hello beast [192.168.0.2], pleased to meet you mail from: <some.user@xxxxxxxxxxx> 250 2.1.0 <some.user@xxxxxxxxxxx>... Sender ok rcpt to: <invalid.user@xxxxxxxxxxxxxx> 550 5.1.1 <invalid.user@xxxxxxxxxxxxxx>... User unknown quit 221 2.0.0 closing connection Connection closed by foreign host. Again, not 100% accurate but works on most setups. HTH Jeff -- redhat-list mailing list unsubscribe mailto:redhat-list-request@xxxxxxxxxx?subject=unsubscribe https://www.redhat.com/mailman/listinfo/redhat-list
