diff --git a/src/mail.js b/src/mail.js
index 030b9cc43..876263d3f 100644
--- a/src/mail.js
+++ b/src/mail.js
@@ -306,7 +306,7 @@ async function checkSpf(domain, mailFqdn) {
 
     let i;
     for (i = 0; i < txtRecords.length; i++) {
-        let txtRecord = txtRecords[i].join(''); // https://agari.zendesk.com/hc/en-us/articles/202952749-How-long-can-my-SPF-record-be-
+        const txtRecord = txtRecords[i].join(''); // https://agari.zendesk.com/hc/en-us/articles/202952749-How-long-can-my-SPF-record-be-
         if (txtRecord.indexOf('v=spf1 ') !== 0) continue; // not SPF
         spf.value = txtRecord;
         spf.status = spf.value.indexOf(` a:${mailFqdn}`) !== -1;
@@ -728,7 +728,7 @@ async function clearDomains() {
 
 // remove all fields that should never be sent out via REST API
 function removePrivateFields(domain) {
-    let result = _.pick(domain, 'domain', 'enabled', 'mailFromValidation', 'catchAll', 'relay', 'banner');
+    const result = _.pick(domain, 'domain', 'enabled', 'mailFromValidation', 'catchAll', 'relay', 'banner');
     if (result.relay.provider !== 'cloudron-smtp') {
         if (result.relay.username === result.relay.password) result.relay.username = constants.SECRET_PLACEHOLDER;
         result.relay.password = constants.SECRET_PLACEHOLDER;
@@ -1132,7 +1132,7 @@ async function updateList(name, domain, data, auditSource) {
 
     name = name.toLowerCase();
 
-    let error = validateName(name);
+    const error = validateName(name);
     if (error) throw error;
 
     for (let i = 0; i < members.length; i++) {
@@ -1169,7 +1169,8 @@ async function resolveList(listName, listDomain) {
     const list = await getList(listName, listDomain);
     if (!list) throw new BoxError(BoxError.NOT_FOUND, 'List not found');
 
-    let resolvedMembers = [], toResolve = list.members.slice(), visited = []; // slice creates a copy of array
+    const resolvedMembers = [], visited = []; // slice creates a copy of array
+    let toResolve = list.members.slice();
 
     while (toResolve.length != 0) {
         const toProcess = toResolve.shift();