Re: [gentoo-user] Filtering spam for a business address
http://www.freesoftwaremagazine.com/articles/focus_spam_postfix/That's a great article.Where do you implement the changes hesuggests on the first page?I searched /etc/postfix/main.cf for the configuration options but they aren't there.- Grant-Just add them to main.cf and do a /etc/init.d/postfix reload (make sure not to include the line numbers in his examples) For the lines that reference external files, you will have to create the files and the content and the issue the command:postmap filenameThe guide puts all of the files in /usr/local/etc/postifx, but I just put the files in /etc/postfix (If you put the files in /etc/postfix instead of /usr/local/etc/postfix, make sure to change the path main.cf). I left off the spf filter since it seems that many people still have not adopted spf. Postgrey is great and I use it on my person email server, but I left that off of the business system I manage. I work for a real estate company and postgrey can delay email by 4 hours or more depending on the sending server configuration. Although no one should depend on email for speedy delivery, it is my experience that most users expect it. All of the other options have really helped a lot and cut down on spam. A couple of things to remember, each time you change main.cf or any other postfix configuration file, you need to issue the command:/etc/init.d/postfix reload to get postfix to take the new configuration changes. Also, if you change any of the external files that main.cf refrences, you need to do a :postmap filenameand then /etc/init.d/postfix reloadIt is probably a good idea to tail your mail logs for a while after you make the changes just to make sure you are not blocking anything you didn't intend to. tail -f /var/log/mail/currentortail -f /var/log/mail.infodepending on your logger.Also, I would recommend sending email to an account on your new system from any and all external email accounts you may have such as yahoo or gmail just for extra testing. Good Luck,Preston
Re: [gentoo-user] Filtering spam for a business address
Does anyone use a spam-filtering solution they think is accurate enough to use with a business email address? I'm getting tons of spam and I'd really like to try and filter it out, but I need to make sure I don't miss any legitimate email. I'm using postfix and courier-imap. - Grant Greylisting because it doesn't filter anything it merely delays email with a temp 450 error. Real emails retry after an interval and spam does not so it eliminates about 90-95%. Couple with reasonable Postfix checks like making sure the sender domain exists, etc and a mail client with internal filtering. With the above in place I see maybe 1-2 actual spams in my inbox a week and averaging about eight a day in my spam folder. Postgrey is in portage and it'll take you about almost two full minutes to get setup and working. I suggest making the the greylist time 30 seconds and the whitelist time 32 days. kashani That sounds really nice. Would you say sending back a 450 error is 100% reliable? Which config option makes postfix check to see if the sender domain exists. I can't find it in /etc/postfix/main.cf. - Grant -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Filtering spam for a business address
Grant wrote: Greylisting because it doesn't filter anything it merely delays email with a temp 450 error. Real emails retry after an interval and spam does not so it eliminates about 90-95%. Couple with reasonable Postfix checks like making sure the sender domain exists, etc and a mail client with internal filtering. With the above in place I see maybe 1-2 actual spams in my inbox a week and averaging about eight a day in my spam folder. Postgrey is in portage and it'll take you about almost two full minutes to get setup and working. I suggest making the the greylist time 30 seconds and the whitelist time 32 days. kashani That sounds really nice. Would you say sending back a 450 error is 100% reliable? Which config option makes postfix check to see if the sender domain exists. I can't find it in /etc/postfix/main.cf. Nothing is 100% reliable and greylisting is no different. Somewhere someone is running a mail server that retries every 4 hours instead of the usual 5 minutes, 15 minutes, 60 minutes that most servers do. Mail that shows up in 4-8 hours may be no different that if you have dropped the mail in the first place. Additionally some things like Amazon newsletters do not retry at all so you'd have to white-list them. And I've seen two instances where email originates from a different server each time it retires... which makes no sense at any level and seems incredibly in efficient. I'd keep an eye on things the first month you run it, but generally I have had very few issues over the past two years. You want to look at smptd_recipient_restrictions. I like the following, but I would not blindly use them unless you are sure it's the behavior you really want. smtpd_recipient_restrictions = reject_invalid_hostname, reject_non_fqdn_recipient, reject_non_fqdn_sender, reject_unknown_sender_domain, reject_unknown_recipient_domain, reject_unauth_pipelining, permit_mynetworks, permit_sasl_authenticated, check_policy_service inet:127.0.0.1:10030, reject_unauth_destination, permit kashani -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Filtering spam for a business address
Grant wrote: Does anyone use a spam-filtering solution they think is accurate enough to use with a business email address?I'm getting tons of spam and I'd really like to try and filter it out, but I need to make sure I don't miss any legitimate email.I'm using postfix and courier-imap. - GrantI have been wondering about this as well and I found this really great write-up: http://www.freesoftwaremagazine.com/articles/focus_spam_postfix/ I would highly recommend looking at it.Preston
Re: [gentoo-user] Filtering spam for a business address
Does anyone use a spam-filtering solution they think is accurate enough to use with a business email address? I'm getting tons of spam and I'd really like to try and filter it out, but I need to make sure I don't miss any legitimate email. I'm using postfix and courier-imap. - Grant I have been wondering about this as well and I found this really great write-up: http://www.freesoftwaremagazine.com/articles/focus_spam_postfix/ I would highly recommend looking at it. Preston That's a great article. Where do you implement the changes he suggests on the first page? I searched /etc/postfix/main.cf for the configuration options but they aren't there. - Grant -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Filtering spam for a business address
Grant wrote: That's a great article. Where do you implement the changes he suggests on the first page? I searched /etc/postfix/main.cf for the configuration options but they aren't there. You have to add them. kashani -- gentoo-user@gentoo.org mailing list
