RE: Spoofed email?

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From: Mike (Mike_at_discussions.microsoft.com)
Date: 03/07/05 

Date: Mon, 7 Mar 2005 15:09:07 -0800

Aaron,

Thanks for taking the time. When you say the "receiver" do you mean our
Exchange box? How do I go about doing a "reverse lookup?"

Thanks,

Mike

"Aaron Tiainen" wrote:

> Mike,
>
> My two cents. The reason why you got this email is that somebody exterally
> to the organisation can send email as if it came from abc@yourdomain.com. If
> the reciever recieves the email and it can't be delivered, then it will send
> a reply back to your email address because it thinks you sent the email.
>
> What the reciever should be doing is performing a reverse lookup on the
> incomming mail. What that does is verify the domain name against the ip
> address it was sent from. This does stop a large amount of crap.
>
> Hope this helps. And, if anybody thinks i am wrong.. .please tell me :)
>
> Thanks
>
> Aaron
>
> "Mike" wrote:
>
> > Greetings,
> >
> > I have a user that occasionally will get a message from Exchange saying:
> >
> >
> >
> > Your message did not reach some or all of the intended recipients.
> >
> >
> >
> > Subject:
> >
> >
> >
> > The following recipient(s) could not be reached:
> >
> >
> >
> > <email address> on 3/7/2005 1:16 AM
> >
> > The e-mail account does not exist at the organization this
> > message was sent to. Check the e-mail address, or contact the recipient
> > directly to find out the correct address.
> >
> > <our Exchange box#5.1.1>
> >
> >
> >
> > <email address> on 3/7/2005 1:16 AM
> >
> > The e-mail account does not exist at the organization this
> > message was sent to. Check the e-mail address, or contact the recipient
> > directly to find out the correct address.
> >
> > <our Exchange box#5.1.1>
> >
> > The list will be a bunch of email addresses that do not exist in our domain.
> > The thing is, he never sent the email in the first place. Is this a case of
> > spoofing?
> >
> > We are running Exchange 2000 SP3 on a WIN2K server, with Outlook 2003. We
> > also have Sybari Antigen with Spam Filtering running on the Exchange box.
> >
> > Any help is appreciated. Thanks in advance.
> >
> > Mike
> >
> >

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