From nobody Thu Apr 27 00:32:12 2023 X-Original-To: freebsd-hackers@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4Q6GsR3kbsz47mg9 for ; Thu, 27 Apr 2023 00:32:27 +0000 (UTC) (envelope-from george+freebsd@m5p.com) Received: from mailhost.m5p.com (mailhost.m5p.com [74.104.188.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "m5p.com", Issuer "R3" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4Q6GsQ315fz3nhQ for ; Thu, 27 Apr 2023 00:32:26 +0000 (UTC) (envelope-from george+freebsd@m5p.com) Authentication-Results: mx1.freebsd.org; dkim=none; spf=pass (mx1.freebsd.org: domain of george+freebsd@m5p.com designates 74.104.188.4 as permitted sender) smtp.mailfrom=george+freebsd@m5p.com; dmarc=none Received: from [IPV6:2001:470:1f07:15ff::26] (court.m5p.com [IPv6:2001:470:1f07:15ff:0:0:0:26]) (authenticated bits=0) by mailhost.m5p.com (8.16.1/8.15.2) with ESMTPSA id 33R0WDXY031599 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO) for ; Wed, 26 Apr 2023 20:32:18 -0400 (EDT) (envelope-from george+freebsd@m5p.com) Message-ID: Date: Wed, 26 Apr 2023 20:32:12 -0400 List-Id: Technical discussions relating to FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-hackers List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-hackers@freebsd.org MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Content-Language: en-US To: FreeBSD Hackers From: George Mitchell Subject: Sendmail, /etc/mail/access, and spam "best practices" Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=0.0 required=10.0 tests=HELO_NO_DOMAIN autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on mattapan.m5p.com X-Spamd-Result: default: False [-1.41 / 15.00]; NEURAL_HAM_MEDIUM(-0.59)[-0.588]; NEURAL_HAM_SHORT(-0.27)[-0.269]; NEURAL_HAM_LONG(-0.26)[-0.255]; R_SPF_ALLOW(-0.20)[+a]; MIME_GOOD(-0.10)[text/plain]; FROM_EQ_ENVFROM(0.00)[]; ASN(0.00)[asn:701, ipnet:74.104.0.0/16, country:US]; MIME_TRACE(0.00)[0:+]; MLMMJ_DEST(0.00)[freebsd-hackers@FreeBSD.org]; TO_DN_ALL(0.00)[]; R_DKIM_NA(0.00)[]; DMARC_NA(0.00)[m5p.com]; RCVD_TLS_ALL(0.00)[]; RCPT_COUNT_ONE(0.00)[1]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_HAS_DN(0.00)[]; PREVIOUSLY_DELIVERED(0.00)[freebsd-hackers@freebsd.org]; TO_MATCH_ENVRCPT_ALL(0.00)[]; ARC_NA(0.00)[]; TAGGED_FROM(0.00)[freebsd] X-Rspamd-Queue-Id: 4Q6GsQ315fz3nhQ X-Spamd-Bar: - X-ThisMailContainsUnwantedMimeParts: N In the hope that a significant number of readers of this message are in charge of email administration, may I ask for guidance on how aggressive you tend to be on using sendmail's /etc/mail/access feature to block email access to substantial portions of address space? I don't want to name any specific entities (corporate or political) as possible targets, but numerous owners of IPv4 /24 blocks, and some /16 blocks and even a few /12 blocks generate an inordinate percentage of the spam messages I have to handle. Right now, I will generally add the specific source of any single spam message to /etc/mail/access, and if I see even only two addresses in the same /24 block, I feel no compunction about blocking the whole /24. Obviously blocking a /16 or a /12 is much more problematic. Thank goodness for abuseat.org, with whose help I daily reject hundreds of messages, and still multiple others still go through. My /etc/mail/access is close to 20,000 entries at this point, though, and it sure is tempting to block some of those /16s, though. -- George