diff --git a/app/models/mailboxes.js b/app/models/mailboxes.js
index 4d1bcd6d3..008c5436c 100644
--- a/app/models/mailboxes.js
+++ b/app/models/mailboxes.js
@@ -176,7 +176,9 @@ Mailboxes.pre('save', async function (next) {
     // default to `alias.retention` or 0
     this.retention = ['\\Trash', '\\Junk'].includes(this.specialUse)
       ? ms('30d')
-      : alias.retention;
+      : typeof alias.retention === 'number'
+      ? alias.retention
+      : 0;
 
     next();
   } catch (err) {
diff --git a/helpers/imap/on-append.js b/helpers/imap/on-append.js
index 086129e4d..b3349529f 100644
--- a/helpers/imap/on-append.js
+++ b/helpers/imap/on-append.js
@@ -146,13 +146,15 @@ async function onAppend(path, flags, date, raw, session, fn) {
     //
     // prepare message for creation
     //
+    const retention =
+      typeof mailbox.retention === 'number' ? mailbox.retention : 0;
     const data = {
       alias: alias._id,
       mailbox: mailbox._id,
       _id: id,
       root: id,
-      exp: mailbox.retention !== 0,
-      rdate: Date.now() + mailbox.retention,
+      exp: retention !== 0,
+      rdate: new Date(Date.now() + retention),
       idate,
       hdate,
       flags,
diff --git a/helpers/imap/on-copy.js b/helpers/imap/on-copy.js
index 17dab5dd5..f6ff67d2d 100644
--- a/helpers/imap/on-copy.js
+++ b/helpers/imap/on-copy.js
@@ -26,7 +26,7 @@ const SocketError = require('#helpers/socket-error');
 const i18n = require('#helpers/i18n');
 const refineAndLogError = require('#helpers/refine-and-log-error');
 
-// eslint-disable-next-line max-params
+// eslint-disable-next-line max-params, complexity
 async function onCopy(connection, mailboxId, update, session, fn) {
   this.logger.debug('COPY', { connection, mailboxId, update, session });
 
@@ -141,8 +141,16 @@ async function onCopy(connection, mailboxId, update, session, fn) {
       message.id = message._id.toString();
       message.mailbox = targetMailbox._id;
       message.uid = updatedMailbox.uidNext;
-      message.exp = targetMailbox.retention !== 0;
-      message.rdate = Date.now() + targetMailbox.retention;
+      message.exp =
+        typeof targetMailbox.retention === 'number'
+          ? targetMailbox.retention !== 0
+          : false;
+      message.rdate = new Date(
+        Date.now() +
+          (typeof targetMailbox.retention === 'number'
+            ? targetMailbox.retention
+            : 0)
+      );
       message.modseq = updatedMailbox.modifyIndex;
       message.junk = targetMailbox.specialUse === '\\Junk';
       message.remoteAddress = session.remoteAddress;
diff --git a/helpers/imap/on-move.js b/helpers/imap/on-move.js
index 1b5fb0036..5270c18f1 100644
--- a/helpers/imap/on-move.js
+++ b/helpers/imap/on-move.js
@@ -190,8 +190,11 @@ async function onMove(mailboxId, update, session, fn) {
         message.id = message._id.toString();
         message.mailbox = targetMailbox._id;
         message.uid = updatedTargetMailbox.uidNext;
-        message.exp = targetMailbox.retention !== 0;
-        message.rdate = Date.now() + targetMailbox.retention;
+        message.exp =
+          typeof targetMailbox.retention === 'number'
+            ? targetMailbox.retention !== 0
+            : false;
+        message.rdate = new Date(Date.now() + (targetMailbox.retention || 0));
         message.modseq = updatedTargetMailbox.modifyIndex;
         message.junk = targetMailbox.specialUse === '\\Junk';
         message.remoteAddress = session.remoteAddress;