Mailing List Archive: SPF: Help

SPF Setup Help

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dmorris1 at lesliekays

Apr 4, 2008, 2:39 PM

Post #1 of 2 (309 views)
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SPF Setup Help

Hi,

In an effort to slow spam I recently turned on SPF, and wanting to ensure our domain wasn't spoofed, I needed to create the appropriate SPF DNS record. I used the wizard to create the record, and the "validator" to check it. I've made the changes in DNS, and everything seems fine; however, I'm worried I missed something. So here are the details:

Our web site and DNS are hosted.
Our one exchange server is behind the firewall via our ISP.
The one exchange server sends and receives email.

MX = mail.lesliekays.com
mail.lesliekays.com = 74.238.84.251
Helo/Ehelo = mail.lesliekays.com

The SPF wizard helped me create this:

v=spf1 mx -all

My biggest concern is that a reverse lookup on 74.238.84.251 shows this DNS record: adsl-074-238-084-251.sip.bct.bellsouth.net.

Am I looking at a potential problem or is the SPF record okay?

Thanks in advance.

Derek

steve at teamITS

Apr 4, 2008, 3:00 PM

Post #2 of 2 (286 views)
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RE: SPF Setup Help [In reply to]

Derek C. Morrissette wrote on 4/4/2008 4:39:09 PM:

> The one exchange server sends and receives email.
>
> MX = mail.lesliekays.com
> mail.lesliekays.com = 74.238.84.251
> Helo/Ehelo = mail.lesliekays.com
>
> The SPF wizard helped me create this:
>
> v=spf1 mx -all

If that is your only source for mail then your record is OK.
You can also save the world some DNS lookups by using:

v=spf1 ip4:74.238.84.251 -all

> My biggest concern is that a reverse lookup on 74.238.84.251 shows
this DNS
> record: adsl-074-238-084-251.sip.bct.bellsouth.net.

The reverse lookup is not relevant to SPF, but some ISPs are
"more suspicious" of mail coming from an address that looks like a
dynamic IP. I think most care more about the message content though.
If you have a static IP and BellSouth is nice they might be able to
change the reverse lookup to mail.lesliekays.com for you.

-----
SPF FAQ: http://www.openspf.org/FAQ
Common mistakes: http://www.openspf.org/FAQ/Common_mistakes

- Steve Yates
- ITS, Inc.
- Not all chemicals are bad. Without chemicals such as hydrogen and
oxygen, for example, there would be no way to make water, a vital
ingredient in beer. --Dave Barry

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