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Outgoing mail and SPF/PTR

Posted on 2011-09-27
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Greetings,

I've been having a recent issue of MAILSPIKE and blacklisting site listing my domain as unsafe, preventing emails from being received by MAILSPIKE users.  Unfortunately, MAILSPIKE is supremely pathetic at providing any information (threat reasoning or contact).  Thus, I'm investigating my network to identify what could be going on.  I have relaying disabled and have examined my logs exhaustively.  I'm looking to implement an SPF record within my DNS, but I suspect limited return on that.  However, I've read nothing to suggest that it could hurt.  However, I have come across an issue that made me need to whip up this inquiry.  Currently, Mailspike is flagging IP address x.x.x.a (my router's WAN IP), while my mail server has x.x.x.b associated with it and the MX record (obviously), which is then NATed to it's private IP.  So, upon setting up a SPF, while I could do similar to the following <domain.com TXT "v=spf1 mx -all">, would that even matter in this case, as the flagged IP is x.x.x.a, not x.x.x.b?  Also, while troubleshooting, it was also suggested that my PTR is incorrect.  However, per http://www.uceprotect.net/en/rblcheck.php, it comes back as correct.  Needless to say, Mailspike and Uceprotect are irritating me, but as a responsible net admin, I do want to resolve the matter.  Would appreciate any pertinent input.  Thanks.  Jer
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Question by:Jer
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by:Papertrip
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If you could provide the hostname and/or IP of your sending servers, I can tell you exactly how it all should be done, and the best way to do it.

SPF record needs to be your sending server(s) IP(s), and on that note, blacklists only affect the sending IP(s) as well.

I'm currently working on another SPF issue at http://www.experts-exchange.com/Networking/Protocols/DNS/Q_27344632.html
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by:Jer
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Papertrip, thanks for the response.  Looked at your other ticket, which seems to be the same issue.  I'm just wondering if I'm supposed to be doing a different config (such as static 1-to-1) for my outgoing mail.  As the IP for WAN port on my central firewall is the route (and address) for all outgoing traffic (SMTP, FTP, HTTP, etc), do I simply create a request (SPF record) for that address x.x.x.a?

Also, when I did discuss creating the record with my ISP who hosts my DNS records, I got a blank stare.  They didn't know what I was talking about.  Does the SPF record get applied elsewhere?

Thanks,

Jer  
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Papertrip earned 500 total points
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If I'm understanding your question and reply correctly, you actually are in a good position right now to do this the "right way".

Set your firewall up so that all outgoing traffic from your mail server goes over x.x.x.b
Create PTR for x.x.x.b that matches the A record of your mail server
Create SPF record with x.x.x.b

Done!

It might help you to wrap your head around all of this stuff if you separate incoming and outgoing mail.  Your MX record has nothing to do with sending mail, only receiving.  Sometimes people get confused when they think that MX and SPF have to match up and things like that.
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by:Jer
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Thanks for the help.  Sorry for the delay in responding.  Been hectic here.
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by:sbenhamou
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Hi

I've done the exact same procedure when changing my ISP, and I'm still in the mailspike blacklist. Since we can't contact them, and since I'm blacklisted each time I change the outgoing IP address, does anyone have an idea how to fix my issue ?
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