fix(core): Remove antispam check (reacherhq#1337)

core/src/lib.rs

@@ -70,7 +70,7 @@ pub mod syntax;
 mod util;
 
 use misc::{check_misc, MiscDetails};
-use mx::{check_mx, is_antispam_mx};
+use mx::check_mx;
 use rand::Rng;
 use smtp::{check_smtp, SmtpDetails, SmtpError};
 use syntax::{check_syntax, get_similar_mail_provider};
@@ -196,6 +196,8 @@ pub async fn check_email(input: &CheckEmailInput) -> CheckEmailOutput {
 	// beginning or end of the list (sorted by priority). Instead, we choose a
 	// random one in the middle of the list.
 	//
+	// See here for explanation: https://cwiki.apache.org/confluence/display/SPAMASSASSIN/OtherTricks
+	//
 	// If anyone has a better algorithm, let me know by creating an issue on
 	// Github.
 	// ref: https://github.com/reacherhq/check-if-email-exists/issues/1049
@@ -204,7 +206,6 @@ pub async fn check_email(input: &CheckEmailInput) -> CheckEmailOutput {
 		.as_ref()
 		.expect("If lookup is error, we already returned. qed.")
 		.iter()
-		.filter(|host| !is_antispam_mx(host.exchange()))
 		.collect::<Vec<&MX>>();
 	mx_records.sort_by_key(|a| a.preference());
 	let host = if mx_records.len() >= 3 {

core/src/mx/mod.rs

@@ -19,7 +19,6 @@ use crate::util::ser_with_display::ser_with_display;
 use async_std_resolver::{lookup::MxLookup, resolver_from_system_conf, ResolveError};
 use serde::{ser::SerializeMap, Serialize, Serializer};
 use std::io::Error;
-use trust_dns_proto::rr::Name;
 
 /// Details about the MX lookup.
 #[derive(Debug)]
@@ -96,12 +95,3 @@ pub async fn check_mx(syntax: &SyntaxDetails) -> Result<MxDetails, MxError> {
 		Err(err) => Ok(MxDetails { lookup: Err(err) }),
 	}
 }
-
-// is_antispam_mx checks if the MX record is an antispam MX record.
-pub fn is_antispam_mx(host: &Name) -> bool {
-	let host = host.to_string();
-	// filter20.antispamcloud.com. (on @computan.net)
-	host.contains("antispamcloud.com") 
-	// mx.spamexperts.com (see https://documentation.n-able.com/spamexperts/userguide/Content/B_Admin%20Level/domains/mx-records.htm)
-	|| host.contains("spamexperts.com")
-}