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Hey folks, Can you guys give me some ideas on how to block e-mail messages coming in through our mail server. Is there some kind of filtering software I can use. Right now I am using exchange 5.5 and we are recieving tons of spam due to all the viruses that are coming out. Your help is appreciated...
hey thanks for the links. You know of anything that will install on a linux box and filter? my company is budget that I have no control over. :-(
I'm confussed, are you running an Exchange 5.5 server on your Linux box?
The best mail server on Linux that I know of is QMail
Documentation can be found here:
http://www.securityfocus.com/guest/5418
http://www.din.or.jp/~ushijima/qmail-conf/install.html
http://servers.linux.com/servers/03/...3.shtml?tid=37
One of several spam blockers for QMail is SPAMBaffle
I am running Exchange 5.5 on a NT4 enviroment. I was just thinking is there such a thing where I can use a linux box as my internet mail gateway with some program to block spam. So before it delivers to my Exchange hopefully it catches most spam.
I'm afraid that now you are starting to complicate things here. As far as I know of there is no way of filtering mail before it reaches the mail server, because filtering is the mailservers job.
The best thing to do would be to use one of the links provided earlier on in order to then install/configure some type of filter onto the Exchange Server.
Try and get a hold of Gore, he knows a lot about Linux servers. He might know of some trick that would allow you to filter mail without a mail server.
Good luck
MrLucifer- Yes you can run a linux server in front of your exchange server to filter mail for you.
The best applications that I am aware of to block spam on a unix(linux) based system are spamassassin or perlMX.
http://au2.spamassassin.org/index.html
PerlMX runs ontop of sendmail. Here is an article that describes it in detail-http://www.perl.com/pub/a/2001/10/10/perlmx.html
All of the mail filtering packages for Exchange require a license to be purchased. If you were going to go the route of putting a 3rd party service on top of exchange, i would recommend upgrading to exchange2000 before putting any 3rd party filtering software on the server. Exchange2k has major improvements over 5.5 in 3rd party filtering functionality.
So basically what you will need to do is change your inbound DNS MX records to point to your new linux server instead of the IMC connector on the Exchange5.5 server. On the linux server I would recommend setting sendmail up to only receive mail at the domains that you host(no relay). Then hardcode the information into sendmail about your exchange5.5 imc in your hosts file. You want to make sure that the linux server is not doing a DNS lookup for your domain as your linux server is now going to be the MX host for your domain. There is a lot of good information on the web about how to configure sendmail as a relay host.
On your exchange5.5 IMC you specify that it should relay all email back out through your new linux server.
The main reason that you want to route the mail back out through the linux server is that you want to have the least amount of services visible to the outside world as possible. I'm guessing that you have a firewall, and right now your exchange5.5 IMC is sitting in the DMZ with access to port25 open. You would want to make sure that you put exchange totally behind the firewall and only allow the linux server to be in the DMZ with port25 access.
This should get you started- http://www.akadia.com/services/sendmail_relay.html
awesome, that is what extactly what I am looking for. Thanks
Since we are taking about this type of info, I have a question. I'm realy a newbie with Exchange by the way.
I'm also using Exchange 5.5. I know Exchange 5.5 have a filter to filter incoming email but I was to filter OUTCOMING email. That my server never send a email outside except if it's from *@MyCompagny.com
The content restrictions in exchange5.5 are very limited... You can only allow/deny all by IP, or you can accept/reject messages on an IMC based on entries you specify from the GAL.
So if you had two different user bases on your exchange server, say half of them have the email addie of [email protected], and the rest are [email protected]. You could go into the content restrictions tab and add everyone from the GAL who has [email protected] to the restricted list. I'm guessing that you have users on your system that you want to be able to send mail internally, but not externally.. That would be the only way to do it.
Are willcard supported?
Could I add *@first.com so all my users can send outside email and that it?
No. In the content restriction tab of the IMC you can only select entries from the GAL. There is no data entry method that would allow you to specify a wildcard. This is one of the things that E2K corrected.
Can I add group?
So basically, if I have 50 users of Exchange (Let said [email protected] , [email protected] , so on until [email protected]), I had all those email address in the content restriction tab of the IMC, only them will be able to send email. All those email who are trying to use my Exchange server was a open relay will be deleted?
Which flavor of Linux do you guys recommend installing SendMail on?
A good post to read is here writen by Gore.
It is a large list of different flavours of Linux and what the differences are.
However if you want my opinion then I'd say SuSE as I belive that it is very easy to configure and secure, as well as robust.
Decided to go with Redhat9 and SpamAssassin. I will keep you guys updated on the project.
Lucifer- The version of linux that you are running really is unimportant. I have never read anything that indicated sendmail runs better on one variant than on another. It is really up to what your comfort level is. If you know redhat better than any other unix variant, use that version. Just make sure that you turn off any services you do not need, and that you patch accordingly.