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Yes, but what do you tell upper level administrators when they find that a major funding source is being jeopardized by untimely email communications? Relying on what you hear from people is convenient but not very sensitive to their real concerns. -----Original Message----- From: Brian Martinez [mailto:[log in to unmask]] Sent: Wednesday, October 24, 2007 1:40 PM To: [log in to unmask] Subject: Re: [MSUNAG] E-mail Issues All, I would like to point to my original in-depth thread on the matter of greylisting: http://list.msu.edu/cgi-bin/wa?A2=ind0704&L=MSUNAG&P=R995&I=-3 Furthermore, I would like to go even more in-depth and touch upon several things to make sure we are all on the same page about this. There are going to be lots of numbers, so please read closely: ------ * A sender only needs to send 1 message, not 3 messages. * A sender does not a receive a flat out rejection, merely a 451 Temporary Error. * A sender not in our database has to go through the greylisting delay, sender's who have passed the test should get through without exception * With a properly configured SMTP server, most senders can get through the greylisting process in well under one hour. * Our SMTP daemons at mail.msu.edu are configured to respond to 451 Temporary Errors as such: retry sending the message every five minutes for fifteen minutes. Failing that, retry the message every ten minutes for one hour. Failing that retry sending the message every two hours for 16 hours, and so on... * As I write this there are currently 1,109,396 hosts who we "trust" Naturally, some of them are spammers, but most of them are not. * The above number grows every single day/hour/minute. ----- The following should give you an idea of the exceptions we make. These folks completely bypass the greylisting process: * We maintain a list of exceptions for nearly all .gov addresses in the United States (we generate it based off of our logs), currently at 4,242 listings * We maintain a list of exceptions for every host here at MSU that carries a valid MX record, currently at 341 listings * We maintain a list of miscellaneous hosts of people who were privy enough to go through our Help Desk and make sure their email goes through as expected. We have helped a few hosts reconfigure their mail servers to meet the RFC spec., currently at 151 listings * We auto-generate a list of larger domains who carry SPF records, AOL, Google, Amazon, Hotmail, Microsoft and more recently Fidelity Investments, currently at 129 listings * The website greylisting.org provides a list of hosts who have difficulty bypassing anybody's greylisting setup. Including Southwest Airlines, MoveOn.org, lists.mysql.com, and ameritradeinfo.com to name a few. This only has 22 entries. ------ You'll note from our stats page: http://project.mail.msu.edu/~rrdtool/spam.php That we have easily dropped 600,000 pieces of spam PER DAY since we implemented greylisting!! Of course spam still does come through, and some legitimate email does get dropped. But with folks knowing that they are expecting a piece of email and it hasn't come through, they know to hit up our Help Desk and we work through to resolve the problem. I have not heard a single complaint about greylisting until just recently, so I hope this helps put things in perspective and helps clear things up a bit. As Nick noted earlier, greylisting is system-wide. It sits as a transparent-bridge between the Internet and mail.msu.edu. The vast majority of people sending to us (nearly 1,110,000 different hosts) do not even know they have gone through greylisting. If there is email _not_being received, the best method for finding out is testing with outside sources first, such as Gmail/Yahoo/Hotmail/etc. Then calling our Help Desk and providing them with full headers from the successfully received message at whatever 3rd party address that was used. We will then investigate the issue and determine if its greylisting or not, and if it is, we will see if it is possible to have their mailer reconfigured properly. If that is outside of the scope of the person attempting to mail us, we will work to add them to our exceptions list (which also seems to grow weekly as of late). Of course, if the issue is not greylisting, we will work to find the appropriate area to move the issue into. If people are so inclined, then anyone is obviously free to migrate elsewhere. I wanted to make sure as many facts as I could recall were clear before anyone decides to go anywhere else. It is a very trustworthy system and the majority of people I hear from swear by it and are quite happy it is in place. Regards, ./brm __________ NOD32 2614 (20071024) Information __________ This message was checked by NOD32 antivirus system. http://www.eset.com