Date: Mon, 14 Feb 2005 10:53:26 -0500 From: Bill Vermillion <bv@wjv.com> To: freebsd-isp@freebsd.org Subject: Re: Sendmail question Message-ID: <20050214155326.GA61258@wjv.com> In-Reply-To: <200502140720.15810.asstec@matik.com.br> References: <1BC9C5447DEF1F4FBE3927A31D6B540404DC0A@gehrig.hall.oopz.com> <200502140720.15810.asstec@matik.com.br>
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Deep in the forest in the dark of night on Mon, Feb 14, 2005 at 07:20 with a cackle and an evil grin Suporte Matik cast another eye of newt into the brew and chanted: > On Monday 14 February 2005 01:33, Noah Davidson wrote: > > > Yes I have the mailertab working as expected. The issue is > > that all rejected mail from the exchange server is bouncing > > back and a copy is sent to the root user's mailbox. This > > bounced mail is filling up the root mailbox. Is there anyway > > to not have the bounced mail go to the root mailbox? > yes! do not send them to root ;) > you must have something misconfigured because the mailgatway > root should not get anything back from your other mailserver > because it is not the sender. I do not know about your exchange > server but if it bounce mail it should go back to the sender MTA > and not to the mailgateway - but if so you have something wrong > IMO We had a client who decided they'd rather have an in-house email server than use ours. We handled their DNS and hosted their web-services also So I repointed the MX records to their machine. A while later I was greeted by a flood of messages in the root mbox as the MS machine was reejecting every piece of mail that was not for a local user and returning them to the sender. Since most messages of this type were spam sent from bogus addresses they were bounced back from the forged address/domain. The solution was simple. I turned off their mail service until they reconfigured their mail server to behave in a more appropriate manner. We were also running as their secondary MX and that was removed at that time. They had two choices - don't abuse our services or find another ISP. > > Thanks > > Noah > > > > ________________________________ > > > > From: owner-freebsd-isp@freebsd.org on behalf of Suporte Matik > > Sent: Sun 2/13/2005 6:11 PM > > To: freebsd-isp@freebsd.org > > Subject: Re: Sendmail question > > > > On Sunday 13 February 2005 23:56, Noah Davidson wrote: > > > This is a backup mail server. The primary mail server is an Exchange > > > 2003 server. So when mail is sent to invaliduser@bdomain.com then this > > > server sends the mail to the exchange server that is responsible for > > > handling the > > > > you wrote: > > > > > I have set up a new FreeBSD box as mainly a backup mail server, > > > > > although it is primary for a couple of domains. It is running > > > > > sendmail 8.13.3 and it works fine, except for all the spam that > > > > but sorry for not understanding your strange crypt ... > > > > > mail for domain.com. Since the user does not exist it bounces the mail. > > > Then the root alias gets a copy of the bounced mail. Is there any way to > > > prevent this from happening? This server should just queue the mail for > > > the exchange server until the exchange server is available. > > > > but anyway you may use /etc/mailertable and put a line like this for each > > domain you forward and there should no additional mail processing until the > > msg timed out conforming your sendmail.cf settings > > > > .domain.com smtp:windots.com.br > > > > aditional you need add to your local-host-names the host name as used in > > the domains MX record > > > > > Thanks > > > Noah Davidson > > > > > > ________________________________ > > > > > > From: owner-freebsd-isp@freebsd.org on behalf of Bill Vermillion > > > Sent: Sun 2/13/2005 5:42 PM > > > To: freebsd-isp@freebsd.org > > > Subject: Re: Sendmail question > > > > > > > > > > > > I know you'll find this hard to believe, but on Sun, Feb 13, 2005 at > > > 23:13 , > > > > > > Suporte Matik actually admitted to saying: > > > > On Sunday 13 February 2005 22:46, Noah Davidson wrote: > > > > > The only problem with that approach is that this is a back up > > > > > server and the users may not be able to know of all of the > > > > > users. Is there any way to not have all of these bounced mail > > > > > go to the postmaster / root account. > > > > > > > > sendmail should reject mail for nonexistent users by default > > > > and not forward to root unless you have any strange alias for > > > > all but you say bounced mail what confuses me a little bit, but > > > > anyway, isn't it that your systema accounts are exploited by > > > > the spammers ? so if having 10 domains you may get 10 spams for > > > > tty in your root mailbox, to prevent you may try this in your > > > > access: > > > > > > > > tty@ ERROR:"4.2.2:450 No such user here." > > > > > > > > and so on for each systema account and rebuild the access.db and > > > > probably your headache goes away > > > > > > The problem I have is that when mail is bounced back mail from > > > spammers often comes from forged addresses and I get emails > > > from the far site indicating there are unknown users. > > > > > > So I find routing noexistant users to /dev/null is more productive. > > > While it's not exactly the best way to do it, there are so many > > > bogus addresses sending mail I haven't found a good alternative. > > > > > > One site we handle has one of those strong standalone names that > > > don't require any advertising to come up #1 on google or msn and > > > when it finally hit 300,000 spams/day for that one domain I took > > > out the MX records. > > > > > > I use the access.db for blocking known places and I won't send > > > anything back at all - I used the DISCARD verb as sending messages > > > back does nothing but generate more traffic. > > > > > > > > ________________________________ > > > > > > > > > > From: Bill Vermillion [mailto:bv@wjv.com] > > > > > Sent: Sun 2/13/2005 2:30 PM > > > > > To: Noah Davidson > > > > > Cc: FreeBSD-ISP List > > > > > Subject: Re: Sendmail question > > > > > > > > > > > > > > > > > > > > Ashes to ashes, and DOS to DOS Noah Davidson was heard to say > > > > > > > > > > on or about Sun, Feb 13, 2005 at 14:10 : > > > > > > I have set up a new FreeBSD box as mainly a backup mail server, > > > > > > although it is primary for a couple of domains. It is running > > > > > > sendmail 8.13.3 and it works fine, except for all the spam that > > > > > > is being sent to it to bad email addresses. I have aliased > > > > > > the root account to an email group on another server so that > > > > > > someone reads the root mail. The problem is that all the mail > > > > > > that spammers are sending to address that do not exist get > > > > > > bounced and the root account a notification (I believe it > > > > > > is the postmaster alias which is aliased to root). Is there > > > > > > any way to not have these notifications sent out. They are > > > > > > filling up the mail boxes. I just want the return to sender, but > > > > > > not to the root / postmaster as well. I have tried using the > > > > > > confCOPY_ERRORS_TO in my .mc file, but that just sends it to an > > > > > > additional account as well. > > > > > > > > > > Making assumptions that your sendmail is receiving bogus mail > > > > > for accounts that you have sendmail receive here is approach you > > > > > can take. > > > > > > > > > > Assume you have domains a.com b.com and c.com and your > > > > > local-host-names has those. > > > > > > > > > > Then you need to find out what users you have for each domain > > > > > > > > > > If you have curly larry and moe on a.com and no one else, then you > > > > > can build a virtualusrtable that looks like this. > > > > > > > > > > curly@a.com curly > > > > > larry@a.com larry > > > > > moe@a.com moe > > > > > @a.com nouser > > > > > > > > > > And the accnount 'nouser' will be in your /etc/mail/aliases > > > > > file and will look like this: > > > > > > > > > > nouser: /dev/null > > > > > > > > > > Run make in /etc/mail to create virtusertable.db and aliases.db > > > > > and that should get rid of the bogus names going to root. > > > > > > > > > > I find the virtualusertable to be quite handy for elminating a lot > > > > > of junk. It will only be a problem if you have a large user > > > > > base or lots of domains. > > > > > > > > > > Bill > > > > > -- > > > > > Bill Vermillion - bv @ wjv . com > > > > > > > > > > > > > > > _______________________________________________ > > > > > freebsd-isp@freebsd.org mailing list > > > > > http://lists.freebsd.org/mailman/listinfo/freebsd-isp > > > > > To unsubscribe, send any mail to > > > > > "freebsd-isp-unsubscribe@freebsd.org" > > > > > > > > -- > > > > > > > > > > > > Infomatik > > > > implementamos asas na sua rede. > > > > (18)3551.3591 (18)8112.7007 > > > > _______________________________________________________ > > > > Participe na lista de seguran?a, > > > > recebendo as mais importantes not?cias na hora > > > > Entre em http://info.matik.com.br e participe. > > > > _______________________________________________________ > > > > Mensagens sem assinatura GPG n?o s?o nossas. > > > > Messages without GPG signature are not from us. > > > > _______________________________________________________ > > > > > > -- > > > Bill Vermillion - bv @ wjv . com > > > _______________________________________________ > > > freebsd-isp@freebsd.org mailing list > > > http://lists.freebsd.org/mailman/listinfo/freebsd-isp > > > To unsubscribe, send any mail to "freebsd-isp-unsubscribe@freebsd.org" > > > > > > > > > _______________________________________________ > > > freebsd-isp@freebsd.org mailing list > > > http://lists.freebsd.org/mailman/listinfo/freebsd-isp > > > To unsubscribe, send any mail to "freebsd-isp-unsubscribe@freebsd.org" > > > > -- > > > > > > Infomatik > > implementamos asas na sua rede. > > (18)3551.3591 (18)8112.7007 > > _______________________________________________________ > > Participe na lista de seguran?a, > > recebendo as mais importantes not?cias na hora > > Entre em http://info.matik.com.br e participe. > > _______________________________________________________ > > Mensagens sem assinatura GPG n?o s?o nossas. > > Messages without GPG signature are not from us. > > _______________________________________________________ > > > > > > _______________________________________________ > > freebsd-isp@freebsd.org mailing list > > http://lists.freebsd.org/mailman/listinfo/freebsd-isp > > To unsubscribe, send any mail to "freebsd-isp-unsubscribe@freebsd.org" > > -- > > > Infomatik > implementamos asas na sua rede. > (18)3551.3591 (18)8112.7007 > _______________________________________________________ > Participe na lista de seguran?a, > recebendo as mais importantes not?cias na hora > Entre em http://info.matik.com.br e participe. > _______________________________________________________ > Mensagens sem assinatura GPG n?o s?o nossas. > Messages without GPG signature are not from us. > _______________________________________________________ -- Bill Vermillion - bv @ wjv . com
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