Re: spam-filtering policy

[Devdas Bhagat <devdas () dvb homelinux org>]

On 13/12/06 11:49 +0800, cc wrote:
> Dear All,
>
> Since there's no 100% effective spam filtering mechanisms
> so far, is it 'effective' to block (every/some) domains/IPs
> and have the admin of those domains/IPs  send an online
> application to whitelist the domains/IPs?
Depending on the volume of mail you handle, it can be. This is
particularly true when you are dealing with NATs, consumer grade
connectivity and dynamic IP addressing issues.

> If it is an effective policy, wouldn't this create more
> of a hassle for the admins of valid/innocent domains?
Those of us who do block large swathes of IP ranges try and minimise
damage.

> If it isn't an effective policy, why does anyone use it?
Because it works better than anything else out there. A spam "tagging"
and filtering policy has the same effect as discarding email. The sender
never gets feedback on delivery. 

About the only time I can justify discarding mail is when it is confirmed
malware and has been accepted in the SMTP transaction (250 in response to
CRLF.CRLF). This is because bouncing that message would do more damage in 
real life than the discard, as the sender address is almost always spoofed.

> The reason why I'm asking is that my co-worker has been
> trying to send an e-mail to a customer whose ISP seems to
> be using such a spam-filtering policy.  This ISP is blocking
> my company's domain, for some stupid reason.  My company
> certainly doesn't spam.
Are they blocking the IP or the domain? Or the IP range? Can you paste
the actual reject message here?

Devdas Bhagat

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