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We have recently started using Office 365 for our email, which requires us to add a DNS TXT record with the value v=spf1 -all. We already have an SPF record with the value v=spf1 ?all for Mandrill, an SMTP sender we also use.

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My concern is this might cause some conflict. Is my concern valid or will be be fine with these two SPF records?

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up vote 22 down vote accepted

You can only have one SPF record.
You need to combine them like so:

v=spf1 -all


v=spf1 ?all
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I'm in exactly the same position here... of implementing line 1 or line 2... whats the difference between -all and ?all – Adrian Salazar Dec 26 '14 at 10:53
@AdrianSalazar -all: mails sent from hosts not specifically allowed are not permitted to send mails. ?all: means any not specified host is neutral and nothing can be said about the validity of it. In practice it is not sent to spam. ?all renders the SPF record almost useless. However some 3rd party provides want you to use it because they change IPs often and don't want that to cause problems. – faker Dec 26 '14 at 11:10

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