From mboxrd@z Thu Jan 1 00:00:00 1970 From: Georg Lehner To: 9fans@cse.psu.edu Subject: Re: [9fans] spam protection vs. secondary mx'es References: Date: Wed, 29 Nov 2006 17:24:59 +0100 In-Reply-To: (Robert Raschke's message of "Wed, 29 Nov 2006 09:35:19 +0000") Message-ID: <87ejrmdxus.fsf@jorgito.magma.com.ni> User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Topicbox-Message-UUID: e81e1578-ead1-11e9-9d60-3106f5b1d025 Hello! Robert Raschke writes: > Hiya, > > how do people use greylisting and /mail/lib/sender protection in the > presence of a secondary MX? > > My greylisting is roughly 80% useless, since spammers appear to know > that a secondary MX will effectively bypass the greylist protection. When using spam protection measures they have to be identical on all MX's of your domain. Some Spammers even try secondary MX's first, since they know that these are most times weeker protected than the main MX. The SMTP protocol is very resilient however, and personally I do not bother to set up secondary MX's for "small" domains, since well behaved mailers will try to reach your MX up to one week before discarding a message. By the way, greylisting takes advantage of this feature too. > Having recently started using /mail/lib/senders, I am seeing a lot of > rejections due to the secondary MX. At the moment it does not really > look like I am loosing any real mailing list traffic, but it is > slightly disconcerting, since a network outage near me will probably > mean I'll be rejecting real traffic once things are back. > > I am starting to question my belief in running my own mail server. Do > people just use gmail or something and not bother with anything else? ... Nowadays running a mailserver is becoming cumbersome. However in the overall picture it is better not to use a mass-mail hoster like yahoo, gmx and the like, because it allows spammers to masquerade their messages behind *@yahoo.com addresses, which you are unlikely to block, since so much other people use them. I have been happy with TMDA for the past three years, it's effectiveness draws from a "blacklist by default" with intelligent whitelisting. If anybody is interested I'll be glad to share my experiences, however TMDA is written in Python and I wouldn't know if it can be made to run on Plan9. Regards, Jorge-Le=F3n