How to specify multiple included domains in SPF record?

Solution 1:

All SPF mechanisms, including include, can be used multiple times, separated by spaces:

"v=spf1 include:_spf.google.com include:otherdomain.com -all"

Evaluation of include works this way:

• If the included data returned PASS, then the include itself generates a result (for example, include:foo.bar generates a PASS, but -include:foo.bar generates a FAIL).

• If the included data returned FAIL or NEUTRAL, then the include does not contribute to the result at all, and processing goes to your next mechanism.

See SPF record syntax and RFC 7208.

(Note that redirect= is not a mechanism but a global modifier, and cannot be repeated this way.)

Solution 2:

This is the correct syntax you requested

domain.com:    IN   TXT    "v=spf1  include:_spf.google.com include:otherdomain.com -all"