diff --git a/FAQ.md b/FAQ.md
index 531434e1ca..7f20657ee9 100644
--- a/FAQ.md
+++ b/FAQ.md
@@ -1522,11 +1522,11 @@ The following authentication methods are supported and used in this order:
 
 * LOGIN
 * PLAIN
+* CRAM-MD5
 * NTLM (untested)
 
-SASL authentication methods, like CRAM-MD5, are not supported
+SASL authentication methods, besides CRAM-MD5, are not supported
 because [JavaMail for Android](https://javaee.github.io/javamail/Android) does not support SASL authentication.
-If using secure connections, a must today, there is little value in using CRAM-MD5 anyway.
 
 If your provider requires an unsupported authentication method, you'll likely get the error message *authentication failed*.
 
diff --git a/app/proguard-rules.pro b/app/proguard-rules.pro
index 40c9810559..2044b1fd8c 100644
--- a/app/proguard-rules.pro
+++ b/app/proguard-rules.pro
@@ -100,3 +100,6 @@
 -dontnote com.bugsnag.android.**
 -dontnote biweekly.io.**
 
+#SASL
+-keep class com.sun.mail.imap.protocol.IMAPSaslAuthenticator
+-keep class com.sun.mail.smtp.SMTPSaslAuthenticator
diff --git a/app/src/main/java/com.sun.mail.imap.protocol/IMAPSaslAuthenticator.java b/app/src/main/java/com.sun.mail.imap.protocol/IMAPSaslAuthenticator.java
new file mode 100644
index 0000000000..a1a79fff0f
--- /dev/null
+++ b/app/src/main/java/com.sun.mail.imap.protocol/IMAPSaslAuthenticator.java
@@ -0,0 +1,103 @@
+package com.sun.mail.imap.protocol;
+
+/*
+    This file is part of FairEmail.
+
+    FairEmail is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    FairEmail is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with FairEmail.  If not, see <http://www.gnu.org/licenses/>.
+
+    Copyright 2018-2020 by Marcel Bokhorst (M66B)
+*/
+
+import android.util.Base64;
+
+import com.sun.mail.iap.Argument;
+import com.sun.mail.iap.ProtocolException;
+import com.sun.mail.iap.Response;
+import com.sun.mail.util.MailLogger;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Properties;
+
+import eu.faircode.email.Helper;
+
+// https://github.com/javaee/javamail/blob/master/mail/src/main/java/com/sun/mail/imap/protocol/IMAPSaslAuthenticator.java
+public class IMAPSaslAuthenticator implements SaslAuthenticator {
+    private IMAPProtocol pr;
+    private String name;
+    private Properties props;
+    private MailLogger logger;
+    private String host;
+
+    public IMAPSaslAuthenticator(
+            IMAPProtocol pr, String name, Properties props,
+            MailLogger logger, String host) {
+        this.pr = pr;
+        this.name = name;
+        this.props = props;
+        this.logger = logger;
+        this.host = host;
+    }
+
+    @Override
+    public boolean authenticate(
+            String[] mechs, final String realm,
+            final String authzid, final String u,
+            final String p) throws ProtocolException {
+
+        if (!pr.hasCapability("AUTH=CRAM-MD5"))
+            throw new UnsupportedOperationException();
+
+        List<Response> v = new ArrayList<>();
+        String tag = null;
+        Response r = null;
+        boolean done = false;
+
+        try {
+            Argument args = new Argument();
+            args.writeAtom("CRAM-MD5");
+            tag = pr.writeCommand("AUTHENTICATE", args);
+        } catch (Exception ex) {
+            r = Response.byeResponse(ex);
+            done = true;
+        }
+
+        while (!done) {
+            try {
+                r = pr.readResponse();
+                if (r.isContinuation()) {
+                    byte[] nonce = Base64.decode(r.getRest(), Base64.NO_WRAP);
+                    String hmac = Helper.HMAC("MD5", 64, p.getBytes(), nonce);
+                    String hash = Base64.encodeToString((u + " " + hmac).getBytes(), Base64.NO_WRAP) + "\r\n";
+                    pr.getIMAPOutputStream().write(hash.getBytes());
+                    pr.getIMAPOutputStream().flush();
+                } else if (r.isTagged() && r.getTag().equals(tag))
+                    done = true;
+                else if (r.isBYE())
+                    done = true;
+            } catch (Exception ex) {
+                r = Response.byeResponse(ex);
+                done = true;
+            }
+            v.add(r);
+        }
+
+        Response[] responses = v.toArray(new Response[0]);
+        pr.handleCapabilityResponse(responses);
+        pr.notifyResponseHandlers(responses);
+        pr.handleLoginResult(r);
+        pr.setCapabilities(r);
+        return true;
+    }
+}
diff --git a/app/src/main/java/com.sun.mail.smtp/SMTPSaslAuthenticator.java b/app/src/main/java/com.sun.mail.smtp/SMTPSaslAuthenticator.java
new file mode 100644
index 0000000000..a76ce2a2db
--- /dev/null
+++ b/app/src/main/java/com.sun.mail.smtp/SMTPSaslAuthenticator.java
@@ -0,0 +1,101 @@
+package com.sun.mail.smtp;
+
+/*
+    This file is part of FairEmail.
+
+    FairEmail is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    FairEmail is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with FairEmail.  If not, see <http://www.gnu.org/licenses/>.
+
+    Copyright 2018-2020 by Marcel Bokhorst (M66B)
+*/
+
+import android.util.Base64;
+
+import com.sun.mail.util.MailLogger;
+
+import java.security.NoSuchAlgorithmException;
+import java.util.Properties;
+
+import javax.mail.MessagingException;
+
+import eu.faircode.email.Helper;
+import eu.faircode.email.Log;
+
+// https://github.com/javaee/javamail/blob/master/mail/src/main/java/com/sun/mail/smtp/SMTPSaslAuthenticator.java
+public class SMTPSaslAuthenticator implements SaslAuthenticator {
+    private SMTPTransport pr;
+    private String name;
+    private Properties props;
+    private MailLogger logger;
+    private String host;
+
+    public SMTPSaslAuthenticator(
+            SMTPTransport pr, String name,
+            Properties props, MailLogger logger, String host) {
+        this.pr = pr;
+        this.name = name;
+        this.props = props;
+        this.logger = logger;
+        this.host = host;
+    }
+
+    @Override
+    public boolean authenticate(
+            String[] mechs, final String realm,
+            final String authzid, final String u,
+            final String p) throws MessagingException {
+
+        if (!pr.supportsAuthentication("CRAM-MD5"))
+            throw new UnsupportedOperationException();
+
+        // https://tools.ietf.org/html/rfc4954
+        int resp = simpleCommand(pr, "AUTH CRAM-MD5");
+        if (resp == 530) { // Authentication is required
+            pr.startTLS();
+            resp = simpleCommand(pr, "AUTH CRAM-MD5");
+        }
+
+        if (resp == 235) // Authentication Succeeded
+            return true;
+
+        if (resp != 334) // server challenge
+            return false;
+
+        try {
+            String t = responseText(pr);
+            byte[] nonce = Base64.decode(t, Base64.NO_WRAP);
+            String hmac = Helper.HMAC("MD5", 64, p.getBytes(), nonce);
+            String hash = Base64.encodeToString((u + " " + hmac).getBytes(), Base64.NO_WRAP);
+            resp = simpleCommand(pr, hash);
+        } catch (NoSuchAlgorithmException ex) {
+            throw new MessagingException("CRAM-MD5", ex);
+        }
+
+        return (resp == 235);
+    }
+
+    private static int simpleCommand(SMTPTransport pr, String command) throws MessagingException {
+        Log.i("SMTP SASL command=" + command);
+        int resp = pr.simpleCommand(command);
+        Log.i("SMTP SASL response=" + pr.getLastServerResponse());
+        return resp;
+    }
+
+    private static String responseText(SMTPTransport pr) {
+        String resp = pr.getLastServerResponse().trim();
+        if (resp.length() > 4)
+            return resp.substring(4);
+        else
+            return "";
+    }
+}
diff --git a/app/src/main/java/eu/faircode/email/Helper.java b/app/src/main/java/eu/faircode/email/Helper.java
index cd6167f395..8cc61c53d6 100644
--- a/app/src/main/java/eu/faircode/email/Helper.java
+++ b/app/src/main/java/eu/faircode/email/Helper.java
@@ -978,6 +978,41 @@ public class Helper {
         void onNothingSelected();
     }
 
+    public static String HMAC(String algo, int blocksize, byte[] key, byte[] text) throws NoSuchAlgorithmException {
+        MessageDigest md = MessageDigest.getInstance(algo);
+
+        if (key.length > blocksize)
+            key = md.digest(key);
+
+        byte[] ipad = new byte[blocksize];
+        byte[] opad = new byte[blocksize];
+
+        for (int i = 0; i < key.length; i++) {
+            ipad[i] = key[i];
+            opad[i] = key[i];
+        }
+
+        for (int i = 0; i < blocksize; i++) {
+            ipad[i] ^= 0x36;
+            opad[i] ^= 0x5c;
+        }
+
+        byte[] digest;
+
+        md.update(ipad);
+        md.update(text);
+        digest = md.digest();
+
+        md.update(opad);
+        md.update(digest);
+        digest = md.digest();
+
+        StringBuilder sb = new StringBuilder();
+        for (byte b : digest)
+            sb.append(String.format("%02x", b));
+        return sb.toString();
+    }
+
     // Miscellaneous
 
     static <T> List<List<T>> chunkList(List<T> list, int size) {
diff --git a/app/src/main/java/eu/faircode/email/MailService.java b/app/src/main/java/eu/faircode/email/MailService.java
index 9c484b4810..8412845da7 100644
--- a/app/src/main/java/eu/faircode/email/MailService.java
+++ b/app/src/main/java/eu/faircode/email/MailService.java
@@ -121,6 +121,8 @@ public class MailService implements AutoCloseable {
         properties.put("mail.event.scope", "folder");
         properties.put("mail.event.executor", executor);
 
+        properties.put("mail." + protocol + ".sasl.enable", "true");
+        properties.put("mail." + protocol + ".sasl.mechanisms", "CRAM-MD5");
         properties.put("mail." + protocol + ".sasl.realm", realm == null ? "" : realm);
         properties.put("mail." + protocol + ".auth.ntlm.domain", realm == null ? "" : realm);