Automatic white-listing from *outgoing* email

Arik Baratz
Wed Jan 1 18:13:22 UTC 2003

> -----Original Message-----
> From: Vernon Schryver []
> The input addresses of mailing lists often differ from their output
> addresses.  For example, how would an automatic whitelisting mechanism
> know from a message to that it should whitelist

The To: header can be examined.

> > Assuming that what is considered 'outgoing' is non-malicious in
> > the spam-war context.
> That assumption is fine for small mail systems where all of the users
> are well known, but it is difficult at a large ISPs.  At least one
> large organization is (or was) using the DCC only on outgoing mail to
> detect and throttle its own spamming users.

A valid point. OTOH, organizational users would IMHO appreciate this feature because it will make sure that no inter-organizational (i.e. from person A at org X to person B in org Y) would cause a false-positive.

> Filtering by the DCC is not perfect.  What if a user responds to spam?
> Responses to spam are amazingly common.  Because the blacklist at
> is indexed by search
> engines, I receive strange messages.  Most such messages are requests
> that I remove unsubscribe them, but yesterday someone asked about
> software to copy DVDs to CDs.  For every user that thinks a blacklist
> is a way to contact spammer, there must be many more who 
> contact spammers
> directly.

Well, I see your point all too well. I agree that in an environment where you deal with many unknown users it is a big problem. I come from an organizational background, where people are (generally) smart enough to hit the Delete key straight away.

> All that asside, if automatic white-listing would work for 
> you or others,
> then please feel free to implement it.  One way to build it would
> be to modify the local mail user agent to add pairs of lines to the
> whiteclnt file.  The first line would be a comment starting with
> '#' with the date of the addition and the second would be meat.  Then
> run a weekly or cron script that would delete entries older 
> than 90 days.
> The same script could search system logs for entries concerning mail
> from white-listed sources and refresh the dates.

Since my organization use Exchange/Outlook, I'd need to write it at the MTA (rather than MUA) level. Now all I need is time.

Arik Baratz
System Engineer

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