diff --git a/src/main.rs b/src/main.rs
index cd31b7a..b2242bd 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,18 +1,19 @@
 use std::io::{self};
-use std::collections::HashMap;
+use std::collections::BTreeMap;
 
 fn main() {
-    let redirects = parse_alias_to_hashmap();
+    let redirects = parse_alias_to_BTreeMap();
     let sieve_script = generate_sieve_script(redirects);
     println!("{}", sieve_script);
 }
 
-fn generate_sieve_script(redirects: HashMap<String, Vec<String>>) -> String {
+fn generate_sieve_script(redirects: BTreeMap<String, Vec<String>>) -> String {
     let mut script : String = "require [\"envelope\", \"copy\"];\n".to_string();
-    for (redirect, destinations) in redirects {
+    for (redirect, mut destinations) in redirects {
         script +=  format!("if envelope :is \"to\" \"{}\" {{\n{}}}\n", redirect,
             (|| {
                 let mut subscript : String = "".to_string();
+                destinations.sort();
                 for destination in destinations.iter().rev().skip(1).rev() {
                     subscript += format!("  redirect :copy \"{}\";\n", destination).as_str();
                 }
@@ -24,9 +25,9 @@ fn generate_sieve_script(redirects: HashMap<String, Vec<String>>) -> String {
     return  script;
 }
 
-fn parse_alias_to_hashmap() -> HashMap<String, Vec<String>> {
+fn parse_alias_to_BTreeMap() -> BTreeMap<String, Vec<String>> {
     // File must exist in the current path
-    let mut redirect_map : HashMap<String, Vec<String>> = HashMap::new();
+    let mut redirect_map : BTreeMap<String, Vec<String>> = BTreeMap::new();
     let mut destinations : Vec<String> = Vec::new();
     for line in io::stdin().lines() {
         let line = line.unwrap();
@@ -46,7 +47,7 @@ fn parse_alias_to_hashmap() -> HashMap<String, Vec<String>> {
     let mut changed = true; 
     while changed {
         changed = false;
-        let mut all_new_redirects : HashMap<String, Vec<String>> = HashMap::new();
+        let mut all_new_redirects : BTreeMap<String, Vec<String>> = BTreeMap::new();
         for destination in destinations.iter() {
             for forward_to in redirect_map.get(destination).unwrap().iter() {
                 if let Some(new_redirects) = redirect_map.get(forward_to) {