svengo Posted October 7, 2021 Share Posted October 7, 2021 I am using the mailcow e-mail stack. Of course I learned the host and all forwarded adrresses. Spamcop has problems parsing the upper received-header which is internal. fd4d:x is an internal and unroutable address (RFC 4193). Interesting is the header underneath, from which the actual sending system can be seen. Return-Path: <firstname.lastname@example.org> Delivered-To: x Received: from mail.svengo.net ([fd4d:6169:6c63:6f77::b]) by 46850f6954c1 with LMTP id IPLuNUsVXmFsxAAAxGfoPw (envelope-from <email@example.com>) for <x>; Wed, 06 Oct 2021 23:29:47 +0200 Received: from cyan.elm.relay.mailchannels.net (cyan.elm.relay.mailchannels.net [220.127.116.11]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.svengo.net (Postcow) with ESMTPS id DC3D01C06D6 for <x>; Wed, 6 Oct 2021 23:29:44 +0200 (CEST) Parsing headers is interrupted: host fd4d:6169:6c63:6f77:0:0:0:b (getting name) no name 0: Received: from mail.svengo.net ([fd4d:6169:6c63:6f77::b]) by 46850f6954c1 with LMTP id IPLuNUsVXmFsxAAAxGfoPw (envelope-from <firstname.lastname@example.org>) for <x>; Wed, 06 Oct 2021 23:29:47 +0200 No unique hostname found for source: fd4d:6169:6c63:6f77:0:0:0:b Possible forgery. Supposed receiving system not associated with any of your mailhosts Will not trust this Received line. Mailhost configuration problem, identified internal IP as source Mailhost: Please correct this situation - register every email address where you receive spam No source IP address found, cannot proceed. Re-learning the host does not work. I am currently removing the header as a workaround. Quote Link to comment Share on other sites More sharing options...
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