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SPF Record with multiple domains
https://forum.linode.com/viewtopic.php?f=11&t=6534
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Author:  FluxDevelopment [ Tue Jan 11, 2011 3:51 pm ]
Post subject:  SPF Record with multiple domains

Hey,

I've read a bunch of threads and THINK I've come up with the right settings, can anyone here look and help verify?

3 domains
1. www.alpha.com
2. www.beta.net
3 www.charlie.org

alpha.com is the primary site on the server I've kept the host name as the default linode one..Not sure if I need to change this.

the mx is mail.alpha.com with smtp.alpha.com as outbound. Below is my TXT Record

"v=spf1 a mx mx:mail.beta.net mx:mail.charlie.org"

In the DNS Settings of beta.net and charlie.org i have set up the mxx records. Note all domains point to the same IP address.

Does the above look correct? I saw some people recommend doing somethign different such as:

"v=spf1 a mx ip4:ip.address.here"

Any ideas on which would be correct?

Thanks

Author:  hawk7000 [ Tue Jan 11, 2011 4:38 pm ]
Post subject:  Re: SPF Record with multiple domains

FluxDevelopment wrote:
Hey,

I've read a bunch of threads and THINK I've come up with the right settings, can anyone here look and help verify?

3 domains
1. www.alpha.com
2. www.beta.net
3 www.charlie.org

alpha.com is the primary site on the server I've kept the host name as the default linode one..Not sure if I need to change this.

the mx is mail.alpha.com with smtp.alpha.com as outbound. Below is my TXT Record

"v=spf1 a mx mx:mail.beta.net mx:mail.charlie.org"

In the DNS Settings of beta.net and charlie.org i have set up the mxx records. Note all domains point to the same IP address.

Does the above look correct? I saw some people recommend doing somethign different such as:

"v=spf1 a mx ip4:ip.address.here"

Any ideas on which would be correct?

Thanks


While what you proposed could theoretically be correct it does look rather a stretch that it would actually be (it would imply rather unconventional mail addresses being used).


It rather seems that you have misunderstood some of the keywords in SPF.

Keep in mind that most of the keywords are kind of shortcuts to including values of dns records found at specified domain names as a way of avoiding to explicitly list all of the IP numbers.

For instance, the "mx" keyword in SPF is a way of including what a specified MX record points to. "mx:example.org", where "example.org" would be the fqdn that has the MX record, would mean that the IP that the name in the MX record(s) found there resolve to are allowed to send mail addressed from this domain name that the SPF record is for.

"a" and "mx" by themselves (no domain name specified) means including the values of A and MX records found at the same fqdn that you are adding the SPF record.


If this is all gibberish to you, you may want to start out with using a wizard such as http://old.openspf.org/wizard.html

Author:  Stever [ Tue Jan 11, 2011 4:39 pm ]
Post subject: 

You will need a separate SPF record for each domain - the fact that they are all hosted on the same server doesn't really make much difference.

Assuming that ALL mail from the domains will be sent through the same server that you are using to receive the mail, the following SPF will work for each domain:
Code:
v=spf1 mx -all


You really only need the other entries if they actually resolve to different IP's.

EDIT: Just to be perfectly clear, you will need to add the above TXT record (or whatever you decide to use) on the alpha.com, beta.net, and charlie.org zones.

Author:  FluxDevelopment [ Tue Jan 11, 2011 4:55 pm ]
Post subject: 

Thanks on both accounts. :)

Author:  zachbrowne [ Fri Jan 21, 2011 10:28 am ]
Post subject:  Try These Links for SPF, Invaluable to Me

http://mxkit.com/webmaster-tools/spf-ge ... ?title=213
http://www.microsoft.com/mscorp/safety/ ... id/wizard/

Zach

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