diff --git a/app/src/main/java/eu/faircode/email/ActivitySetup.java b/app/src/main/java/eu/faircode/email/ActivitySetup.java
index 9916a06281..6e12018beb 100644
--- a/app/src/main/java/eu/faircode/email/ActivitySetup.java
+++ b/app/src/main/java/eu/faircode/email/ActivitySetup.java
@@ -84,6 +84,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.OutputStream;
+import java.security.Principal;
 import java.security.SecureRandom;
 import java.security.cert.CertificateException;
 import java.security.cert.CertificateFactory;
@@ -1101,6 +1102,31 @@ public class ActivitySetup extends ActivityBase implements FragmentManager.OnBac
 
                     String fingerprint = EntityCertificate.getFingerprint(cert);
                     List<String> emails = EntityCertificate.getAltSubjectName(cert);
+                    if (emails.size() == 0) {
+                        Principal principal = cert.getSubjectDN();
+                        if (principal != null) {
+                            String subject = principal.getName();
+                            if (subject != null) {
+                                Log.i("Parsing subject=" + subject);
+                                for (String p : subject.split(",")) {
+                                    String[] kv = p.split("=");
+                                    if (kv.length == 2) {
+                                        String key = kv[0].trim();
+                                        String value = kv[1].trim().toLowerCase();
+                                        if (Helper.EMAIL_ADDRESS.matcher(value).matches() &&
+                                                ("CN".equalsIgnoreCase(key) ||
+                                                        "emailAddress".equalsIgnoreCase(key))) {
+                                            if (!emails.contains(value))
+                                                emails.add(value);
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                    }
+
+                    if (emails.size() == 0)
+                        throw new IllegalArgumentException("No email address found in key");
 
                     DB db = DB.getInstance(context);
                     for (String email : emails) {