Weird Problem with MailScanner

[Hugo van der Kooij]

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Damian Rivas wrote:
> I have sendmail, not postfix as my MTA. I've been checking and I have to download some packages like access_db to prevent Backscattering.
> 
> I'll explain how things work here so that you can give me more accurate advice:
> 
> I have a MX Linux server on the outside which is the one experimenting the weird problem, caused surely by the backscattering. Then, I have an internal MS Exchange 2003 server which recieves the filtered and scanned mails and sends the mails via SMTP to the MX Linux Server to be scanned before being sent.
> 
> I can activate SMTP filtering in Exchange but the problem is that it checks the contacts in AD, if I don't have that contact it doesn't send the mail. Why is it a problem? As I stated before, this is a Travel Agency and is constantly recieving mails from new hotels, airlines, agencies, etc. With "new" I mean that they were unknown contacts until the reception of their mail, therefore there domain is not identified as a trusted or real one. So, if I use the MS Exchange filtering this will likely block the answers to this new domains.
> 
> So the filtering, in my opinion should be done only in the MailScanner server, the thing is that I want to know which is your recommendation to build the filtering on sendmail and if there can be a solution with the MS Exchange filtering, perhaps I misunderstood the documentation.

You need to verify recipient addresses on the Exchange server. If you
can make sure that Exchange will not accept dummy address on SMTP
sessions you can use this to make sure you do not accept them on your
sendmail server either. I can't quote the exact syntax for sendmail or
the knob on the Exchange screens as I use neither.

Hugo.

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hvdkooij at vanderkooij.org               http://hugo.vanderkooij.org/
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	A: Yes.
	>Q: Are you sure?
	>>A: Because it reverses the logical flow of conversation.
	>>>Q: Why is top posting frowned upon?

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