Yep, I do agree and block without question systems that connect to my gateways and announce my own hostname or ip address in their helo string. Or messages that contain non-printable or lot's of 8-bit content in the headers, or illegal hostnames, etc. But for the most part, we try not to be too aggressive in this vein.
Bill ----- Original Message ----- From: "Chris Scott" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Saturday, August 16, 2003 10:05 AM Subject: Re: [IMail Forum] Anyone have any experiences with Postini ? > David Sullivan wrote: > > > There are a couple of items I think should be distinguished that may > > affect everyone's point of view. > > <snip some very good comments> > > > > So...I think that's what this whole discussion comes down to...cost > > and benefit. Multiple test rejection is great, but as volumes grow you > > just can't rely on it solely unless your willing to accept the exponentially increasing costs. > > At some point, you've got to start adding some single failures in. > > Good points, all of them. Many single tests are sufficient for most people > to reject on regardless of the results of other tests. A few I can think of: > -RCPT TO: a non-existent user. Self explanatory. > -MAIL FROM: a sender that isn't a syntactically correct email address > or from an invalid domain. If I can't reach them by email, why should I > accept theirs? > -HELO as my MTA's IP address/hostname and it isn't my MTA. My MTA can't > send to itself from outside itself. > > There are probably more I'm missing and some I've omitted since I'm tired of > typing already today. If I reject on these alone, I'm saving resources > (processor, disk, bandwidth, etc.). Why waste those resources on other > tests when I know these should be an absolute reject? > > There are also some tests I may not want to rely on alone but in conjunction > with other tests, they allow me to make an accept/reject decision. > > > > > Again, IMHO the best combination is a carefully balanced mix between > > single failure rejection AND weighting. > > > > Very good advice. The issue, just like spam, isn't black and white. > > > -- > Chris Scott > Host Orlando, Inc. > http://www.hostorlando.com/ > > > > To Unsubscribe: http://www.ipswitch.com/support/mailing-lists.html > List Archive: http://www.mail-archive.com/imail_forum%40list.ipswitch.com/ > Knowledge Base/FAQ: http://www.ipswitch.com/support/IMail/ > To Unsubscribe: http://www.ipswitch.com/support/mailing-lists.html List Archive: http://www.mail-archive.com/imail_forum%40list.ipswitch.com/ Knowledge Base/FAQ: http://www.ipswitch.com/support/IMail/
