I have a quick question regarding SPF records: Do they need to be present for all subdomains?
Lets say that I have a TXT record with SPF info for domain.com
Let’s also say that I have a seperate email domain for subdomain.domain.com
Will the SPF policy/info for domain.com also apply to the subdomain? Or do I need to add a separate TXT record for that too?
You need to have separate SPF records for each subdomain you wish to send mail from.
The following was originally posted on openspf.org, which used to be a great resource for this kind of thing.
Latest link http://www.open-spf.org/FAQ/The_demon_question/
The Demon Question: What about subdomains?
If I get mail from
pielovers.demon.co.uk, and there’s no SPF data for pielovers, should I
go back one level and test SPF for demon.co.uk? No. Each subdomain at
Demon is a different customer, and each customer might have their own
policy. It wouldn’t make sense for Demon’s policy to apply to all its
customers by default; if Demon wants to do that, it can set up SPF
records for each subdomain.
So the advice to SPF publishers is this: you should add an SPF record
for each subdomain or hostname that has an A or MX record.
Sites with wildcard A or MX records should also have a wildcard SPF
record, of the form: * IN TXT “v=spf1 -all”
This makes sense - a subdomain may very well be in a different geographical location and have a very different SPF definition.
The ‘include:’ directive for SPF may be used to provide all subdomains with the same entries. For example, on the SPF record for subdomain mailfrom.example.com enter ‘include:example.com’. In this fashion whenever you update the definition for example.com your subdomains will automatically pick up the updated values.