Thank you.
It does not appear that your ISP is publishing a TXT record for SPF.
The two relay servers you cited are both on the same /24 subnet:
Non-authoritative answer:
Name: irgb10.truemail.co.th
Address: 203.144.173.226
Non-authoritative answer:
Name: irpkscout3.truemail.co.th
Address: 203.144.173.143
You might get away with listing just those two IPs, or listing the entire /24.
However, you correctly point out that your ISP may move the servers to other IPs.
If you must relay through their server, your best solution may be, as Hannah suggested, to contact your ISP and ask them for a list of outbound MX IPs .. or even better, ask them to publish a (-all) SPF record.
Alternately, stop relaying through their mail server and simply send mail directly.
If your ISP will not let you send outbound mail directly, and refuses to publish an SPF record, and cannot guarantee fixed IPs for their outbound mail servers, you might also secure services from a company who offers SMTP relay services.
-john
At 09:07 AM 3/1/2010, you wrote:
>Ok.
>
>my domain is compassitsolutions.com
>
>I send email out from my domain but for some domain destinations is gets relayed to mail.truemail.co.th
>When I check headers mail is sent out of ISP servers such as irgb10.truemail.co.th irpkscout3.truemail.co.th and a couple of others.
>
>So the SPF record needs to be for my domain (MX records) and also for the relay servers.
>
>
>I managed to get it working with a IP4: subnet declaration, but I would like to know if I can use the domain for truemail.co.th in case their IP scheme changes.
>
>Thanks,
>Harold
>
>________________________________________
>From: John Blazek [spf.pobox@logicalsolutns.com]
>Sent: Monday, March 01, 2010 9:36 PM
>To: spf-help@v2.listbox.com
>Subject: Re: [spf-help] help with SPF record for unknown hosts
>
>Hello,
>
>You'll get much better results here if you use real domain names.
>
>Based on the assumption that "relayisp.com" is ficticious, the best we can offer is a guess.
>
>If you provide your ISP's domain name, you might get a very simple working answer.
>
>-john
>
>
>
>At 03:25 AM 3/1/2010, you wrote:
>>I relay mail through the ISP and I would like to know if it is possible to make something like *.relayisp.com
>>
>>I don't know all of the servers that the ISP will send mail out from or if they change their hostnames.
>>
>>They might have 3 servers such as: mail1.relayisp.com mail2.relayisp.com mail3.relayisp.com
>>
>>is it possible to achieve something like this:
>>"v=spf1 mx a:*.relayisp.com -all"
>>
>>Thanks,
>>Harold
>>
>>
>>
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>
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