Email users 2004-02-06 - By Ed Wilts
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On Fri, Feb 06, 2004 at 05:57:17PM +0300, 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.
In general, this is not possible. For example, on my work system, the
incoming mail hits a Linux system on the outside, gets rerouted to
another Linux system on the inside, and then if it doesn 't know anything
about the user, gets sent over to MS Exchange. If Exchange doesn 't know
about the address, the mail bounces. The key thing is that the e-mail
server you talk to (the first Linux system) has no knowledge of me at
all - it just assumes the e-mail is valid and passes it on.
> Or without sending email to him, how can I know, is there a such user
> ivantan@(protected) ?.
Even by sending e-mail to him, you don 't really know. The mail may be
quietly dropped in the bit bucket on the receiving system, or it may be
automatically processed by some software application. It may be
forwarded to another external e-mail address which may or may not
bounce the message.
In some cases, you can ask the receiving MTA if the user is valid and it
may tell you. In many cases, however, there 's no way to know.
--
Ed Wilts, Mounds View, MN, USA
mailto:ewilts@(protected)
Member #1, Red Hat Community Ambassador Program
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