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Please help me to create SPF record that will be helpful to validate my outgoing mail. Here is my server environment.

We hosted an application at one hosting provider. Though he provided mail services, we are not using it. Instead we are using GoogleApps for official mail purpose. For this we already configured SPF record as "v=spf1 include:_spf.google.com ~all".

Along with this we have newly configured another SMTP server to use it for sending newsletters, promotional mails to our website visitors, as there are some limitations in usage of number of emails per day with GoogleApps.

We want to have both email services: GoogleApps and new SMTP server. In such cases, how can we create SPF record mentioning both IP addresses? Here is my new SMTP server IP: 45.23.77.65

Thanks in advance, Max

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4 Answers 4

In order for SPF to be any real benefit, you need to aim for a -all default action. To do this you need to ALWAYS use your designated mail servers to handle your mail, which isn't too hard, but means in particular that home users can't use their ISPs mail servers, which in turn means they need to use SSL/TLS (or non-standard ports) as so many ISPs block port 25 other than to their own servers.

It's considered courteous to list explicit IPs first since they require no addtional DNS lookups (so they're faster too) and SPF rules are evaluated left to right. For a single IP, you don't need the /32 on the end as that's implicit. All in all,

v=spf1 ip4:45.23.77.65 include:_spf.google.com -all

Having done that, create a SenderID record containing this:

spf2.0/pra

This says that you don't publish any "purported responsible address" records (which are somewhat broken anyway), but also makes SenderID defer to SPF for permitted mail sources. This syntax is functionaly identical to the suggested spf2.0/pra ?all that Microsoft's somewhat buggy wizard will suggest. When you're done, register your domain with Microsoft. This will mean that hotmail and friends subscribe to your DNS explicitly, again helping mail get delivered faster.

I'd steer clear of MS' wizard for spf1 records; the openspf one is more reliable. Remember that SenderID (a.k.a. SPF 2.0) does not in any way replace or obsolete standard SPF; you should use both (and DKIM while you're at it, though that's harder).

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v=spf1 include:_spf.google.com ip4:45.23.77.65/32 ~all
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It would just be:

"v=spf a mx ip4:45.23.77.65 invlude:_spf.google.com ~all"

Below is a example of our record, which involves a lot more IPs. "v=spf a max ip4:X.X.X.X ipv4:Y.Y.Y.Y inv4:Z.Z.Z.Z include:spflocal.domain.com -all"

Then we have another SPF record called spflocal.domain.com and that has another big list of IP addresses and subnets in it for all of our local IPs. You can branch off as many SPF records as you need to since there is a limit to how many you can have per record.

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"a" and "mx" are unnecessary based on his current example, and will just cause extra lookups on the receiving machine. Is there no way to consolidate your ip4 records via CIDR? Multi-level includes are generally something to be avoided if not strictly necessary. –  BMDan Jun 28 '10 at 13:34

Try this Microsoft link as well, it will walk you through the process, and create your record for you at the end.

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