diff --git a/lib/handlers/on-copy.js b/lib/handlers/on-copy.js
index a692396c..25a319c8 100644
--- a/lib/handlers/on-copy.js
+++ b/lib/handlers/on-copy.js
@@ -132,6 +132,12 @@ async function copyHandler(server, messageHandler, connection, mailbox, update,
 
     notifyLongRunning();
 
+    let targetMailboxEncrypted = false;
+
+    if (targetData.encryptMessages) {
+        targetMailboxEncrypted = true;
+    }
+
     try {
         while ((messageData = await cursor.next())) {
             tools.checkSocket(socket); // do we even have to copy anything?
@@ -141,6 +147,12 @@ async function copyHandler(server, messageHandler, connection, mailbox, update,
                 uid: messageData.uid,
                 _id: messageData._id
             };
+
+            const parsedHeader = (messageData.mimeTree && messageData.mimeTree.parsedHeader) || {};
+            const parsedContentType = parsedHeader['content-type'];
+
+            const isMessageEncrypted = parsedContentType ? parsedContentType.subtype === 'encrypted' : false;
+
             // Copying is not done in bulk to minimize risk of going out of sync with incremental UIDs
             sourceUid.unshift(messageData.uid);
             let item = await db.database.collection('mailboxes').findOneAndUpdate(
@@ -218,6 +230,84 @@ async function copyHandler(server, messageHandler, connection, mailbox, update,
                 { writeConcern: 'majority' }
             );
 
+            const newPrepared = await new Promise((resolve, reject) => {
+                if (targetMailboxEncrypted && !isMessageEncrypted && userData.pubKey) {
+                    // encrypt message
+                    const outputStream = messageHandler.indexer.rebuild(messageData.mimeTree).value; // get raw rebuilder stream
+                    let raw = Buffer.from([], 'binary'); // set initial raw
+
+                    outputStream
+                        .on('data', data => {
+                            raw = Buffer.concat([raw, data]);
+                        })
+                        .on('end', () => {
+                            messageHandler.encryptMessages(userData.pubKey || '', raw, (err, res) => {
+                                if (err) {
+                                    return reject(err);
+                                }
+
+                                // encrypted rebuilt raw
+
+                                if (res) {
+                                    messageHandler.prepareMessage({ raw: res }, (err, prepared) => {
+                                        if (err) {
+                                            return reject(err);
+                                        }
+                                        // prepared new message structure from encrypted raw
+
+                                        const maildata = messageHandler.indexer.getMaildata(prepared.mimeTree);
+
+                                        // add attachments of encrypted messages
+                                        if (maildata.attachments && maildata.attachments.length) {
+                                            messageData.attachments = maildata.attachments;
+                                            messageData.ha = maildata.attachments.some(a => !a.related);
+                                        } else {
+                                            messageData.ha = false;
+                                        }
+
+                                        // remove fields that may leak data in FE or DB
+                                        delete messageData.text;
+                                        delete messageData.html;
+                                        messageData.intro = '';
+
+                                        messageHandler.indexer.storeNodeBodies(maildata, prepared.mimeTree, err => {
+                                            // store new attachments
+                                            let cleanup = () => {
+                                                let attachmentIds = Object.keys(prepared.mimeTree.attachmentMap || {}).map(
+                                                    key => prepared.mimeTree.attachmentMap[key]
+                                                );
+
+                                                messageHandler.attachmentStorage.deleteMany(attachmentIds, maildata.magic);
+
+                                                if (err) {
+                                                    return reject(err);
+                                                }
+                                            };
+
+                                            if (err) {
+                                                return cleanup(err);
+                                            }
+
+                                            return resolve(prepared);
+                                        });
+                                    });
+                                }
+                            });
+                        });
+                } else {
+                    resolve(false);
+                }
+            });
+
+            // replace fields
+            if (newPrepared) {
+                messageData.mimeTree = newPrepared.mimeTree;
+                messageData.size = newPrepared.size;
+                messageData.bodystructure = newPrepared.bodystructure;
+                messageData.envelope = newPrepared.envelope;
+                messageData.headers = newPrepared.headers;
+            }
+
             let r = await db.database.collection('messages').insertOne(messageData, { writeConcern: 'majority' });
 
             if (!r || !r.acknowledged) {