* Forwarded (from: personal) by mark lewis using timEd/2 1.10.y2k+.   
   * Originally from waldo kitty (1:3634/1000) to mark lewis (1:3634/12).   
   * Original dated: Tue Mar 17, 13:24   
      
   -------- Forwarded Message --------   
   Subject: Re: [Weasel] 450 Errors In Weasel Pro   
   Date: Mon, 16 Mar 2015 19:14:23 +1100   
   From: Peter Moylan    
   Reply-To: weasel-list@os2voice.org   
   To: weasel-list@os2voice.org   
      
   On 16/03/15 16:46, Steven Levine wrote:   
   > In <550664ED.9020001@pmoylan.org>, on 03/16/15   
   > at 04:06 PM, Peter Moylan said:   
   >   
   > Hi Peter,   
   >   
   >> The "return path not verifiable" usually means that the receiving server   
   >> is trying to check that the claimed sender's address is a genuine mail   
   >> account. Typically it does this by starting a "send mail" transaction to   
   >> the address named in the MAIL FROM command, but aborting it before   
   >> actually sending anything. If this attempt fails, it concludes that the   
   >> send in the MAIL FROM command is a fake.   
   >   
   > Is this still true for a significant number of today's MTAs? I was under   
   > the impression that these days most use SPF or one of its successors.   
      
   I don't know how common each method is, but the wording "return path not   
   verifiable" seems to me to point to a test of the return path rather   
   than an SPF check.   
      
   >> In this case, though, it appears to be checking the _recipient's_   
   >> address (robert.wolfe@winserver.us), and discovering that winserver.us   
   >> will not accept mail for robert.wolfe.   
   >   
   > I don't read it this way. As I read the logs, it is the comcast   
   > mailserver that is rejecting the MAIL FROM with a 450.   
   >   
   > Reading between the lines, the MAIL FROM is foo@os2bbs.org and the RCPT TO   
   > is robert.wolfe@winserver.us.   
      
   Thanks, I missed seeing that. In that case I think I know what the   
   problem is -- see below.   
      
   >> Maybe we need to see a longer section of the log to work this out.   
   >   
   > We also need to know what the senders MX record looks like. If we assume   
   > that mail.os2bbs.org is the mx then the reject make sense if the comcast   
   > mail server does SPF validation.   
      
   Here's the problem, as I see it:   
      
   [D:\Dev4\NumAnaly]nslookup -type=MX os2bbs.org   
   Server: RTA1046VW.home   
   Address: 192.168.1.1   
      
   Non-authoritative answer:   
   os2bbs.org preference = 0, mail exchanger = mail.os2bbs.org   
      
   Authoritative answers can be found from:   
   mail.os2bbs.org internet address = 50.194.33.5   
      
   [D:\Dev4\NumAnaly]nslookup 50.194.33.15   
   Server: RTA1046VW.home   
   Address: 192.168.1.1   
      
   Name: 50-194-33-15-static.hfc.comcastbusiness.net   
   Address: 50.194.33.15   
      
   The problem is that the hostname   
   50-194-33-15-static.hfc.comcastbusiness.net does not match os2bbs.org. I   
   used to run into similar problems before I configured Weasel to use my   
   ISP's mail server as a backup relay.   
      
   There are two possible solutions:   
      
   (a) Convince comcastbusiness.net to put something into their nameserver   
   to map 50.194.33.15 to os2bbs.org. Some ISPs will do this for you.   
   Others will charge you for a static IP address but not follow through on   
   the nameserver implications.   
      
   (b) Configure Weasel to use a relay server as backup, to handle the mail   
   that is rejected because of the reverse DNS lookup problem.   
      
   --    
   Peter Moylan peter@pmoylan.org http://www.pmoylan.org   
      
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