diff --git a/api.js b/api.js
index 08641c6..a47ddb8 100644
--- a/api.js
+++ b/api.js
@@ -145,10 +145,7 @@ if (config.api.secure && certOptions.key) {
     let httpsServerOptions = {};
 
     httpsServerOptions.key = certOptions.key;
-    if (certOptions.ca) {
-        httpsServerOptions.ca = certOptions.ca;
-    }
-    httpsServerOptions.cert = certOptions.cert;
+    httpsServerOptions.cert = tools.buildCertChain(certOptions.cert, certOptions.ca);
 
     let defaultSecureContext = tls.createSecureContext(httpsServerOptions);
 
@@ -534,10 +531,7 @@ module.exports = done => {
         namespace: 'mail'
     });
 
-    if (config.acme && config.acme.agent && config.acme.agent.enabled) {
-        acmeRoutes(db, server, { disableRedirect: true });
-    }
-
+    acmeRoutes(db, server, { disableRedirect: true });
     usersRoutes(db, server, userHandler, settingsHandler);
     addressesRoutes(db, server, userHandler, settingsHandler);
     mailboxesRoutes(db, server, mailboxHandler);
diff --git a/imap-core/lib/tls-options.js b/imap-core/lib/tls-options.js
index 3e02a98..2a82b06 100644
--- a/imap-core/lib/tls-options.js
+++ b/imap-core/lib/tls-options.js
@@ -54,7 +54,8 @@ const tlsDefaults = {
         '-----END CERTIFICATE-----',
     honorCipherOrder: true,
     requestOCSP: false,
-    sessionIdContext: crypto.createHash('sha1').update(process.argv.join(' ')).digest('hex').slice(0, 32)
+    sessionIdContext: crypto.createHash('sha1').update(process.argv.join(' ')).digest('hex').slice(0, 32),
+    minVersion: 'TLSv1'
 };
 
 /**
diff --git a/lib/cert-handler.js b/lib/cert-handler.js
index b19542b..ccf8c96 100644
--- a/lib/cert-handler.js
+++ b/lib/cert-handler.js
@@ -295,8 +295,6 @@ class CertHandler {
             certData.cert = cert;
         }
 
-        certData.ca = [].concat(ca || []);
-
         if (primaryCert) {
             try {
                 const parsedCert = forge.pki.certificateFromPem(primaryCert);
@@ -558,7 +556,11 @@ class CertHandler {
         // key might be encrypted
         let privateKey = await decrypt(certData.privateKey, this.secret, this.cipher);
 
-        let serviceCtxOpts = { key: privateKey, cert: certData.cert, ca: certData.ca };
+        let serviceCtxOpts = {
+            key: privateKey,
+            cert: tools.buildCertChain(certData.cert, certData.ca)
+        };
+
         for (let key of ['dhparam']) {
             if (serverOptions[key]) {
                 serviceCtxOpts[key] = serverOptions[key];
diff --git a/lib/certs.js b/lib/certs.js
index ca1357a..bfb6454 100644
--- a/lib/certs.js
+++ b/lib/certs.js
@@ -4,6 +4,7 @@ const config = require('wild-config');
 const fs = require('fs');
 const db = require('./db');
 const CertHandler = require('./cert-handler');
+const { buildCertChain } = require('./tools');
 
 const certs = new Map();
 const servers = [];
@@ -92,12 +93,7 @@ module.exports.loadTLSOptions = (serverOptions, name) => {
 
     if (serverCerts) {
         serverOptions.key = serverCerts.key;
-
-        if (serverCerts.ca) {
-            serverOptions.ca = serverCerts.ca;
-        }
-
-        serverOptions.cert = serverCerts.cert;
+        serverOptions.cert = buildCertChain(serverCerts.cert, serverCerts.ca);
 
         if (serverCerts.dhparam) {
             serverOptions.dhparam = serverCerts.dhparam;
@@ -130,13 +126,12 @@ config.on('reload', () => {
         let certOptions = {};
         if (serverCerts) {
             certOptions.key = serverCerts.key;
-            if (serverCerts.ca) {
-                certOptions.ca = serverCerts.ca;
-            }
-            certOptions.cert = serverCerts.cert;
+            certOptions.cert = buildCertChain(serverCerts.cert, serverCerts.ca);
+
             if (serverCerts.dhparam) {
                 certOptions.dhparam = serverCerts.dhparam;
             }
+
             entry.server.updateSecureContext(certOptions);
         }
     });
diff --git a/lib/tools.js b/lib/tools.js
index c5ed6f2..6374c07 100644
--- a/lib/tools.js
+++ b/lib/tools.js
@@ -1,3 +1,4 @@
+/* eslint no-control-regex: 0 */
 'use strict';
 
 const os = require('os');
@@ -586,6 +587,24 @@ function roundTime(seconds) {
     return `${seconds} ${seconds === 1 ? 'second' : 'seconds'}`;
 }
 
+function parsePemBundle(bundle) {
+    bundle = (bundle || '').toString().split(/\r?\n/).join('\x00');
+    let matches = bundle.match(/[-]{3,}BEGIN [^-]+[-]{3,}.*?[-]{3,}END [^-]+[-]{3,}/g);
+    if (matches) {
+        matches = Array.from(matches).map(cert => cert.replace(/\x00/g, '\n') + '\n');
+    }
+    return matches;
+}
+
+function buildCertChain(cert, ca) {
+    return [cert]
+        .concat(ca || [])
+        .flatMap(ca => ca)
+        .map(ca => ca.trim() + '\n')
+        .filter(ca => ca.trim())
+        .join('\n');
+}
+
 module.exports = {
     normalizeAddress,
     normalizeDomain,
@@ -609,6 +628,8 @@ module.exports = {
     formatFingerprint,
     getEnabled2fa,
     roundTime,
+    parsePemBundle,
+    buildCertChain,
 
     formatMetaData: metaData => {
         if (typeof metaData === 'string') {