Re: [IMail Forum] A small question about unknown user

[NetQuick Mail Administration]

----- Original Message -----
From: "ARC Lan Administrator" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, November 24, 2000 11:16 AM
Subject: Re: [IMail Forum] A small question about unknown user


> Yes, I understand, but my problem is:
>
> 1. Someone([EMAIL PROTECTED]) sent a mail to a mailing list ([EMAIL PROTECTED]).
> 2. There is an non-exist e-mail address([EMAIL PROTECTED]) in the
> [EMAIL PROTECTED] list.
> 3. [EMAIL PROTECTED] sent a mail to [EMAIL PROTECTED], and then [EMAIL PROTECTED]
> broadcast this mail to all members, right?

    Spot on so far.

> 4. [EMAIL PROTECTED] does not know there is no [EMAIL PROTECTED] , so the
mail
> will be rejected, right?

    The message will be sent and rejected back to the sending address.  I
don't think it sends one to the reply to address (the list).

> 5. IMail will reject the mail for [EMAIL PROTECTED] , but IMail won't
return
> an error message to that list -- [EMAIL PROTECTED], right?
> 6. So the list - [EMAIL PROTECTED] and the sender - [EMAIL PROTECTED] won't get
the
> error return message -- "550 unknown user", right?
> 7. Thus, the list - [EMAIL PROTECTED] and the sender - [EMAIL PROTECTED] won't
know
> there is no [EMAIL PROTECTED] or this e-mail address is not valid.
So....the
> sender or the list will send mails to [EMAIL PROTECTED] again and again.

    The list is the sending agent in this and it needs to corect the
problem.  You could create a nobody address and have it forward the unknown
user mail to the hostmaster for that domain and send an autoreply to the
list telling it what  the problem is with that address.  Hopefully the list
owners reads theit own list and will catch the problem.  I'm not sure how
the mailbox full and other admin messages handle this.

> 8. So, my question is "Does there have any possiblity to return an error
> message to the real sender when there is an unknown e-mail address by
using
> IMail Server?"

    Why?  THe real sender can not usually fix the problem if it is in a
list.  That is the responsibility of the list owner/moderator.

> Think about this, if there is a spammer, he/she sent more then 20000 mails
> to unknown users in your IMail Server everyday........It sounds like
another
> kind of DoS attack, isn't it?

    Sounds like?  If it looks like a duck, walks like a duck and quacks like
a duck, IT"S A DUCK.  While this may be an unintended DOS, it's still a form
of DOS.

Kevin Childers

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