FYI -- my response (see original below) / pmw - - The original note follows - - Date: Thu, 20 Jun 1996 10:45:48 EDT From: Peter M. Weiss <[log in to unmask]> Subject: Re: Studies on Internet Reliability I too run a list that has approx 5k users on it. Distributions are about once per three weeks. I would say that about one per cent bounce even after I've cleaned up the carnage i.e., list maintenance, from the previous distribution. Lot's of unknown userids (real unknowns or temporary because the target's authentication system db was down), unknown hosts (temporary or permanent because one of the authoritative DNS was fubar), host config points to itself (didn't they notice that no one was getting e-mail????). -- co-owner: INFOSYS, TQM-L, CPARK-L, ERAPPA-L, JANITORS, LDBASE-L, et -L URL:mailto:[log in to unmask] "Do you suffer from analysis paralysis?" <original posting ...> Date: Wed, 19 Jun 96 09:53:00 CST From: [log in to unmask] Subject: Studies on Internet Reliability Sender: [log in to unmask] I am presently taking a graduate course towards my masters in telecommunications management'. I am looking for any studies that have been done regarding the reliability of Internet email or other measures of Internet reliability. One of the types of data might be if a thousand messages were sent, what per cent arrived within one minute, within ten minutes, within an hour, within a day, were not received, etc. Any other measures of reliability would be helpful as well. If anyone knows of any data like this, I'd be grateful if they could email me at: [log in to unmask] Thanks in advance for your assistance. Fred [TELECOM Digest Editor's Note: I can tell you from my own experience with the Digest mailing list which has about five thousand names at any given time I get back 150-200 mail daemons from each issue (if I do five issues that day that means about a thousand daemons) which indicate trouble was encountered in delivery. Deducting the 'user unknown' daemons which are the only ones I can do anything about (I remove those names from the list after two or three such returns on any given name, and there are usually two or three such removals daily), I still get a good number of daemons which complain about delivery problems. Typically the problem will be 'host unknown' or 'host not receiving mail, will keep trying' or 'cannot resolve host name'. Sometimes the name resolvers are hosed; that is they got a bit scrambled up and for the time being don't know where to go to find (or seek resolution for) a given domain or site, etc. A dozen or so daemons each time say 'timed out during user open with site.name' and this generally means when the delivering site went calling on the receiving site it got there and 'knocked on the window' (connected to the appropriate socket) and the receiving site 'opened the window' alright, but got impatient and slammed the window shut before delivery was completed. Or so the sending site thought ... or maybe the delivering site stood there for the longest time waiting for the receiving site to accept the mail and finally gave up and went away leaving the recieving site still waiting for more mail, etc. Maybe the item of mail did not terminate to the satisfaction of the receiving site, etc. In all probability the mail did get delivered just as it gets delivered eventually to places where initially the report was 'host unknown'. Typically an issue of this Digest takes about 18 hours for complete delivery to all names on the list, and I have the list sorted from the '@' sign to the right so that all users at a given site get serviced at the same time, which sendmail would do anyway but by sorting it in advance sendmail does not have to 'work so hard' to find everything going to the same place; that sorting seems to cut a couple hours off the total time. At any given time around the clock usually I have four or five instantiations of sendmail running; if I start them sooner than about an hour apart (like say two within thirty minutes of each other) they will 'race each other' as they each benefit from the hostname lookups the other one is doing and this causes some people to get a later issue of the Digest a few minutes before they get an earlier issue (i.e. one does a lookup and has it in the place where those things are stored; another sendmail comes along looking and finds the information the first one had squirreled away and uses it also). Typically the mailqueue has ten to twelve thousand names waiting for delivery when I am working on several issues in a day's time. I just now did a check on it with the command 'mailq | wc' (meaning just count the lines, don't send me the whole %$$#* stdout) and the response was 8708 deliveries pending. Sometimes I forget the '| wc' part of that request then I sit here and cuss while screen after screen is dumped at me. <grin> I encourage everyone to learn about sendmail and how it works. The documentation is only about two thousand pages long or the size of an Ayn Rand novel and good for reading before bedtime. <more grin> PAT]