Spam service (#269)

spam/proto/spam.proto

@@ -0,0 +1,30 @@
+syntax = "proto3";
+
+package spam;
+
+option go_package = "./proto;spam";
+
+service Spam {
+	rpc Classify(ClassifyRequest) returns (ClassifyResponse) {}
+}
+
+// Check whether an email is likely to be spam based on its attributes
+message ClassifyRequest {
+	// The body of the email
+	string email_body = 1;
+	// The email address it is being sent to
+	string to = 2;
+	// The email address it has been sent from
+	string from = 3;
+	// The subject of the email
+	string subject = 4;
+}
+
+message ClassifyResponse {
+	// Is it spam? Returns true if its score is > 5
+	bool is_spam = 1;
+	// The score evaluated for this email. A higher number means it is more likely to be spam
+	double score = 2;
+	// The rules that have contributed to this score
+	repeated string details = 3;
+}