---------- Original Message ---------------------------------- From: Bernard Dugas bernard.dugas@is-production.com Date: Fri, 16 Feb 2007 10:22:25 +0100
Schmid wrote:
Well to use other SMTP relay than the one from the used ISP is not allways possible, and should be prevented anyway.
Why ? there is no risk if encryotion/authentication is used.
Where do you enforce authentication is there a directsender ?
i was not send direct email from an ogo device as well, somewhere port 25 getting lost between my ogo and the relay. i'm just able to use bluewin's relay .. init7 prevent even port 25 out of dialup range .... a lot more do the same ..
nearly 100% of the spam is caused by direct senders, very seldom they use the ISP's Relay. so lets close that big spamfriendly hole.
This is why SPF + authentication on outgoing smtp should avoid this "direct senders" spam origin.
authentication is no security as most email client use chaching passwords to authenticate, at least outlook have a interface to use this mechanissm to send email from third party programm.
anyway .. blackholing outbound port 25 will let all the complicated be obsolete .. and cost's nothing. and blacklisting of Dynamic ranges is very effective, but some ISP do not follow RFC in namingconvention of PTR's and will be detected as Dynamic. even they dont care after getting noted about the reason why some servers are not able to send email because of listesd as dynamic IP.
Sad as high prized Admins just ignoring the real world and dreaming about some expensive and timeconsuming construction about analyzing the content.. and doing some strange other things to prevent spamer's
Best regards,
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