Slashdot Mirror
Stopping Spammers Who Exploit Secondary MX?
drteknikal asks: "I'm the admin for a small law firm. We use our ISP as our secondary mx. We are receiving spam from our secondary mx even when our primary has been continually available. We suspect that spammers are routing to our secondary MX to bypass the DNS-based spam filtering on our primary. After examining some of the traffic, our ISP agrees. Neither of us sees an immediate solution, given the purpose and function of secondary MX. They already restrict relaying to hosts on their network. Has anyone else seen this? Does anyone have suggestions on how an ISP could secure their mail exchangers without interfering with the functionality required to function as secondary MX for an external domain?"
"Don't fumble through boring man pages. Try my product!" - Richard M. Stallman, GNU Founder and CEO
GNU GVideo GProfessor is the leader in computer learning. We have taught over 5 million people, and we can teach you GNU/Linux, GNU/Emacs, GNU/gcc, and more! GNU GVideo GProfessor was founded in 1983 to provide consumers with training on software for their personal computers. Since that time, millions have successfully used and learned from GNU GVideo GProfessor's fool-proof "What-You-See-Is-What-You-Do" teaching method. The first lesson, GNU
It's FAST! You'll be up and running in an hour! Don't waste time sifting through man pages, commuting to classes or seminars. Just pop in the CD-ROM and you're learning!
It's EASY! It's as simple as 1-2-3! GNU GVideo GProfessor's straightforward "What-You -See-Is-What-You-Do" approach makes learning as easy as watching TV!
It's CONVENIENT! We're ready to teach you day and night! With your busy schedule, you don't have time to waste at classes or seminars. Don't fumble through boring man pages. Whatever your schedule, we're ready when you are!
It's COMPLETE! These aren't short teaser lessons. Each 60-minute lesson takes you from installing the software to more advanced skills. And they're not just for beginners! We'll surprise you with the knowledge you'll gain!
Why Am I Making This Incredible Offer? I'm so confident that once you try my exceptional " What-You-See-Is-What-You-Do" learning method, you'll turn to us for all your computer learning needs.
* How it works!
The bonus gift and ANY TWO of the three computer learning CD-ROMs are yours free without further obligation, PERIOD. Take 10 days to decide if you want to keep the complete set of CDs. After your 10 day free trial, if you decide to keep the complete set, we'll conveniently bill your credit card just $69.95. Or simply contact our customer care number at rtfm@gnu.org if you decide to return any one of the lessons, and you will be charged nothing more!
Every day hundreds of people just like you learn with GNU GVideo GProfessor this same fast and easy way. If you decide to keep all three lessons, every five weeks you will continue learning by automatically receiving other GNU GVideo GProfessor subjects you have an interest in, billed on the same exact terms as your first shipment. Or simply call and cancel. Everything is up to you! But most important, you are never under any obligation to purchase a subject that you don't keep. Best of all, the bonus gift, and your choice of any two of the three computer learning CD-ROMs are yours to keep FREE!
a
"Don't fumble through boring man pages. Try my product!" - Richard M. Stallman, GNU Founder and CEO
GNU GVideo GProfessor is the leader in computer learning. We have taught over 5 million people, and we can teach you GNU/Linux, GNU/Emacs, GNU/gcc, and more! GNU GVideo GProfessor was founded in 1983 to provide consumers with training on software for their personal computers. Since that time, millions have successfully used and learned from GNU GVideo GProfessor's fool-proof "What-You-See-Is-What-You-Do" teaching method. The first lesson, GNU
It's FAST! You'll be up and running in an hour! Don't waste time sifting through man pages, commuting to classes or seminars. Just pop in the CD-ROM and you're learning!
It's EASY! It's as simple as 1-2-3! GNU GVideo GProfessor's straightforward "What-You -See-Is-What-You-Do" approach makes learning as easy as watching TV!
It's CONVENIENT! We're ready to teach you day and night! With your busy schedule, you don't have time to waste at classes or seminars. Don't fumble through boring man pages. Whatever your schedule, we're ready when you are!
It's COMPLETE! These aren't short teaser lessons. Each 60-minute lesson takes you from installing the software to more advanced skills. And they're not just for beginners! We'll surprise you with the knowledge you'll gain!
Why Am I Making This Incredible Offer? I'm so confident that once you try my exceptional " What-You-See-Is-What-You-Do" learning method, you'll turn to us for all your computer learning needs.
* How it works!
The bonus gift and ANY TWO of the three computer learning CD-ROMs are yours free without further obligation, PERIOD. Take 10 days to decide if you want to keep the complete set of CDs. After your 10 day free trial, if you decide to keep the complete set, we'll conveniently bill your credit card just $69.95. Or simply contact our customer care number at rtfm@gnu.org if you decide to return any one of the lessons, and you will be charged nothing more!
Every day hundreds of people just like you learn with GNU GVideo GProfessor this same fast and easy way. If you decide to keep all three lessons, every five weeks you will continue learning by automatically receiving other GNU GVideo GProfessor subjects you have an interest in, billed on the same exact terms as your first shipment. Or simply call and cancel. Everything is up to you! But most important, you are never under any obligation to purchase a subject that you don't keep. Best of all, the bonus gift, and your choice of any two of the three computer learning CD-ROMs are yours to keep FREE!
_,.