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email - Adding an SPF record for a 3rd party, but don't have one for my own domain

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We have a 3rd party service sending
some email on our behalf. They are using our domain name in their outgoing emails. They
have requested we configure an SPF record for
them.



We do not currently have an SPF record
defined for our own domain, which is the same one the 3rd party is
"spoofing".




My concern is that if we
add a record for a 3rd party without defining our own as well that mail originating from
our servers could be rejected.



Is my concern
valid?



Answer




If you have no SPF record then receivers
will generally fail safe and accept your email (although that's starting to change). As
soon as you provide an SPF record you must include all legitimate
mail senders, because otherwise the ones not listed could be treated as possible forgery
sources.



Strictly speaking, you can
include ~all or ?all and avoid listing
all your mail senders, but if you do that you won't get any benefit from the SPF record
other than for testing that it's otherwise
accurate.



Ideally your third parties
will already have a generic SPF record and you can just add the
include:spf.thirdparty.dom element to your record. If they
don't you might well want to create your own record for them and chain it youself
anyway, so that it's easy for you manage
administratively.




For example, if you
are
contoso.com:



thirdparty1.spf.contoso.com
            txt 'v=spf1 ... -all' # list their mail senders for
            you
thirdparty2.spf.contoso.com txt 'v=spf1 ... -all' # list their mail
            senders for you
spf.contoso.com txt 'v=spf1 ... -all' # list your mail
            senders
contoso.com txt 'v=spf1 include:spf.contoso.com
            include:thirdpart1.spf.contoso.com include:thirdparty2.spf.contoso.com
            -all'


/>


Some useful
resources:




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