Vous devez to have separate SPF records for chaque subdomain you wish to send mail from.
The suivant was originally posted on openspf.org, qui 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, et il y a no SPF data for pielovers, should I
go back one level et test SPF for demon.co.uk? No. Each subdomain at
Demon is a différent customer, et chaque customer might have leur own
policy. It ne voudrait pas make sense for Demon's policy to apply to tous its
customers par défaut; si Demon wants to do that, it can set up SPF
records for chaque subdomain.
So le advice to SPF publishers is this: you should ajoutez unn SPF record
for chaque subdomain ou hostname that has an A ou MX record.
Sites avec wildcard A ou MX records should aussi have a wildcard SPF
record, of le form: * IN TXT "v=spf1 -all"
This makes sense - a subdomain may très well be in a différent geographical location et have a très différent SPF definition.
The 'include:' directive for SPF may be used to provide tous subdomains avec le même entries. Par exemple, on le SPF record for subdomain mailfrom.example.com enter 'include:example.com'. In this fashion whenever you mettez à jour le definition par exemple.com votre subdomains will automatically pick up le updated values.
