On Thu, Dec 09, 2004 at 10:06:32PM +0800, Ow Mun Heng wrote: > In that case, in some cases, eg: if one runs their own mail-server, > grey-listing seems to be a better option compared to spamassassin, even > when using SURBL. > > Reason being, greylisting stops it at the MTA level, spamassassin only > tracks it once it's already in the system. greylisting doesn't stop it all. There are a bunch of well-behaved mail servers out there sending spam and if you don't have spamassassin or some such tool installed, you will get spam. I turned on greylisting last night on my home server and still had 10 spam messages by morning that spamassassin/procmail had delivered to by spam folder. A coworker turned on greylisting on his home system last night and discovered that a message from the mrtg mailing list was initially blocked but not retried. In other words, a legitimate message that should have been delivered went to the bit bucket. You can make a perfectly valid case that the server that tried to deliver it is broken, but you can also make a perfectly valid case that you're now preventing legitimate e-mail from being delivered. Yes, you can add specific hosts to a whitelist but that requires manual maintenance and sometimes can't be detected until *after* you've prevented delivery. In a large corporate environment, it's too late to add a server to a whitelist - you may have already lost an order, frustrated a customer, or at least added maintenance work for your e-mail admins. There is no single free one-step method for stopping all spam and nothing but the spam. -- Ed Wilts, RHCE Mounds View, MN, USA mailto:ewilts@xxxxxxxxxx Member #1, Red Hat Community Ambassador Program
