Re: [Mailman-Users] Mailman and recipient spam filtering
Andrew Daviel writes: > My real question is, there are two types of "permanent" (500 series) > rejection - recipient problems and message problems. I want mailman to > auto-unsubscribe stale addresses after 5 (bounce_score_threshold) > bounces, but I don't want active addresses to be unsubscribed because 5 > successive viruses or spams got through a relatively quiet list but were > rejected by the recipient's filters. Expanding on what Mark wrote: It's not possible to reliably distinguish the two cases. Besides the large number of sites that give uninformative status codes to policy (ie, "message problem") rejections, DMARC rejects get a "message problem" status code, but they indicate that you just aren't going to get through to that recipient. If somebody who's had different experience wants to try the experiment and show that it actually has potential for reducing undesired unsubscriptions, I don't mean to discourage them. But I won't do it -- in my experience, such spates of spam getting through the list are miniscule compared to the problems caused by rude and incompetent receivers, so the effort is excessive compared to the return. Steve -- Mailman-Users mailing list Mailman-Users@python.org https://mail.python.org/mailman/listinfo/mailman-users Mailman FAQ: http://wiki.list.org/x/AgA3 Security Policy: http://wiki.list.org/x/QIA9 Searchable Archives: http://www.mail-archive.com/mailman-users%40python.org/ Unsubscribe: https://mail.python.org/mailman/options/mailman-users/archive%40jab.org
Re: [Mailman-Users] Mailman and recipient spam filtering
On 04/06/2016 07:01 PM, Andrew Daviel wrote: > > My real question is, there are two types of "permanent" (500 series) > rejection - recipient problems and message problems. I want mailman to > auto-unsubscribe stale addresses after 5 (bounce_score_threshold) > bounces, but I don't want active addresses to be unsubscribed because 5 > successive viruses or spams got through a relatively quiet list but were > rejected by the recipient's filters. > > I wondered if that was already handled inside mailman bounce processing, > or is something that needs work. Mailman does not distinguish between various types of 5xx permanent failures. If Mailman receives a 5xx status during SMTP to the outgoing MTA, that is recorded as a bounce. If it receives a permanent failure DSN returned by a remote MTA, that is recorded as a bounce. You can adjust the parameters bounce_score_threshold and bounce_info_stale_after in Bounce Processing to try to accommodate differences in those situations, but ultimately, Mailman doesn't distinguish between a permanent failure for non-existent address and one for unacceptable content. -- Mark Sapiro The highway is for gamblers, San Francisco Bay Area, Californiabetter use your sense - B. Dylan -- Mailman-Users mailing list Mailman-Users@python.org https://mail.python.org/mailman/listinfo/mailman-users Mailman FAQ: http://wiki.list.org/x/AgA3 Security Policy: http://wiki.list.org/x/QIA9 Searchable Archives: http://www.mail-archive.com/mailman-users%40python.org/ Unsubscribe: https://mail.python.org/mailman/options/mailman-users/archive%40jab.org
Re: [Mailman-Users] Mailman and recipient spam filtering
On Mon, 4 Apr 2016, Rich Kulawiec wrote: On Mon, Apr 04, 2016 at 05:30:13PM -0700, Andrew Daviel wrote: I have an incident where a rejection message was forwarded to a list, and on to other members. I don't know if that was even mailman, but it got me thinking. First, that's because the system which originated the rejection is broken. On further investigation, that incident was not mailman or real mailing list software, just a simple address expansion in sendmail to 4 people. The sender had spoofed the sending address to the recipient, i.e. "list" address. All mail systems doing anti-spam/anti-virus/anti-whatever should *always* reject (if they're going to reject) during the SMTP conversation (a) because that's most effective and efficient and (b) because that avoids generating a bounce message, which in turn avoids backscatter such as you've described. Yes; the antivirus system works like that. It was sendmail generating a DSN back to the "sender" that caused the problem, and I think I can just reject mail "from" that address, i.e. make it a receive-only address, e.g. Joe and Jane both get mail to "webmaster" but reply as themselves. Second, anything coming back should go to the Sender:, which I believe defaults to: LISTNAME-bounces@LISTHOST This doesn't necessarily yield the desired outcome, e.g., it may result in incrementing the bounce count for a subscriber when that shouldn't really happen, but at least it avoids forwarding backscatter to an entire mailing list. Apologies, I confused the issue by talking about two different things, backscatter and bounces. My real question is, there are two types of "permanent" (500 series) rejection - recipient problems and message problems. I want mailman to auto-unsubscribe stale addresses after 5 (bounce_score_threshold) bounces, but I don't want active addresses to be unsubscribed because 5 successive viruses or spams got through a relatively quiet list but were rejected by the recipient's filters. I wondered if that was already handled inside mailman bounce processing, or is something that needs work. -- Andrew Daviel, TRIUMF, Canada -- Mailman-Users mailing list Mailman-Users@python.org https://mail.python.org/mailman/listinfo/mailman-users Mailman FAQ: http://wiki.list.org/x/AgA3 Security Policy: http://wiki.list.org/x/QIA9 Searchable Archives: http://www.mail-archive.com/mailman-users%40python.org/ Unsubscribe: https://mail.python.org/mailman/options/mailman-users/archive%40jab.org
Re: [Mailman-Users] Mailman and recipient spam filtering
On Mon, Apr 04, 2016 at 05:30:13PM -0700, Andrew Daviel wrote: > I have an incident where a rejection message was forwarded to a > list, and on to other members. I don't know if that was even > mailman, but it got me thinking. First, that's because the system which originated the rejection is broken. All mail systems doing anti-spam/anti-virus/anti-whatever should *always* reject (if they're going to reject) during the SMTP conversation (a) because that's most effective and efficient and (b) because that avoids generating a bounce message, which in turn avoids backscatter such as you've described. Second, anything coming back should go to the Sender:, which I believe defaults to: LISTNAME-bounces@LISTHOST I believe that LISTNAME-bounces, in turn, should be sent by the MTA in play to: "|/usr/local/mailman/mail/mailman bounces LISTNAME" (although I have it set up like this in the sendmail aliases file: LISTNAME-bounces:"|/usr/local/mailman/mail/mailman bounces LISTNAME", postmaster@LISTHOST so that the local postmaster gets a copy of the bounce for examination.) This doesn't necessarily yield the desired outcome, e.g., it may result in incrementing the bounce count for a subscriber when that shouldn't really happen, but at least it avoids forwarding backscatter to an entire mailing list. ---rsk -- Mailman-Users mailing list Mailman-Users@python.org https://mail.python.org/mailman/listinfo/mailman-users Mailman FAQ: http://wiki.list.org/x/AgA3 Security Policy: http://wiki.list.org/x/QIA9 Searchable Archives: http://www.mail-archive.com/mailman-users%40python.org/ Unsubscribe: https://mail.python.org/mailman/options/mailman-users/archive%40jab.org
