diff --git a/src/core/imap/MCIMAPSession.cpp b/src/core/imap/MCIMAPSession.cpp
index 56e918374..59b44d044 100644
--- a/src/core/imap/MCIMAPSession.cpp
+++ b/src/core/imap/MCIMAPSession.cpp
@@ -685,6 +685,12 @@ void IMAPSession::connect(ErrorCode * pError)
             * pError = ErrorTLSNotAvailable;
             goto close;
         }
+        if (!checkCertificate()) {
+            MCLog("StartTLS ssl connect certificate ERROR %d", r);
+            * pError = ErrorCertificate;
+            goto close;
+        }
+
         break;
 
         case ConnectionTypeTLS:
@@ -701,14 +707,14 @@ void IMAPSession::connect(ErrorCode * pError)
                                                     setMailStreamSSLContextServerName,
                                                     const_cast<void*>(static_cast<const void*>(MCUTF8(mHostname))));
 #endif
-        MCLog("ssl connect %s %u %u", MCUTF8(mHostname), mPort, r);
+        MCLog("TLS ssl connect %s %u %u", MCUTF8(mHostname), mPort, r);
         if (hasError(r)) {
             MCLog("connect error %i", r);
             * pError = ErrorConnection;
             goto close;
         }
         if (!checkCertificate()) {
-            MCLog("ssl connect certificate ERROR %d", r);
+            MCLog("TLS ssl connect certificate ERROR %d", r);
             * pError = ErrorCertificate;
             goto close;
         }