diff --git a/lib/interac_email.rb b/lib/interac_email.rb
index b12b045da6a9444f56d0d58a5c3b0c9f33c85ac9..1a46120cfe3893d54114a99cc6c3bd0f4f4dfafb 100644
--- a/lib/interac_email.rb
+++ b/lib/interac_email.rb
@@ -119,17 +119,17 @@ class InteracEmail
 		end
 
 		def authentication_header
-			@m["Authentication-Results"]&.value
+			Array(@m["Authentication-Results"]).map(&:value)
 		end
 
 		HEADER_REGEX = /\sheader.d=payments.interac.ca\s/.freeze
 
 		def ensure_authentication_header
-			auth = authentication_header
-
+			auth = authentication_header.find { |a|
+				a =~ HEADER_REGEX
+			}
 			raise Error::NoAuth, @m unless auth
 			raise Error::BadAuth, @m unless auth =~ /\sdkim=pass\s/
-			raise Error::BadDomain, @m unless auth =~ HEADER_REGEX
 		end
 
 		def dkim_header
diff --git a/test/test_interac_email.rb b/test/test_interac_email.rb
new file mode 100644
index 0000000000000000000000000000000000000000..b54a60bac68012bf2aa95bb8deb8c541ac889358
--- /dev/null
+++ b/test/test_interac_email.rb
@@ -0,0 +1,75 @@
+# frozen_string_literal: true
+
+require "interac_email"
+require "mail"
+require "test_helper"
+
+class InteracEmailTest < Minitest::Test
+	def test_authentication_header
+		@m = Mail.new(<<~MAIL)
+			Authentication-Results: hai
+			To: someone@example.com
+			From: interac@example.com
+
+			body
+		MAIL
+		@validator = InteracEmail::Validator.new(@m)
+		assert_equal ["hai"], @validator.authentication_header
+	end
+
+	def test_authentication_headers
+		@m = Mail.new(<<~MAIL)
+			Authentication-Results: hai
+			Authentication-Results: hai2
+			To: someone@example.com
+			From: interac@example.com
+
+			body
+		MAIL
+		@validator = InteracEmail::Validator.new(@m)
+		assert_equal ["hai", "hai2"], @validator.authentication_header
+	end
+
+	def test_ensure_authentication_header
+		@m = Mail.new(<<~MAIL)
+			Authentication-Results: stuff header.d=payments.interac.ca dkim=pass and
+			Authentication-Results: and
+			To: someone@example.com
+			From: interac@example.com
+
+			body
+		MAIL
+		@validator = InteracEmail::Validator.new(@m)
+		@validator.ensure_authentication_header
+	end
+
+	def test_ensure_authentication_header_fail
+		@m = Mail.new(<<~MAIL)
+			Authentication-Results: stuff header.d=payments.interac.ca dkim=fail and
+			Authentication-Results: and
+			To: someone@example.com
+			From: interac@example.com
+
+			body
+		MAIL
+		@validator = InteracEmail::Validator.new(@m)
+		assert_raises(InteracEmail::Error::BadAuth) do
+			@validator.ensure_authentication_header
+		end
+	end
+
+	def test_ensure_authentication_header_no_interac
+		@m = Mail.new(<<~MAIL)
+			Authentication-Results: stuff header.d=fakey.fake dkim=pass and
+			Authentication-Results: and dkim=pass stuff
+			To: someone@example.com
+			From: interac@example.com
+
+			body
+		MAIL
+		@validator = InteracEmail::Validator.new(@m)
+		assert_raises(InteracEmail::Error::NoAuth) do
+			@validator.ensure_authentication_header
+		end
+	end
+end