diff --git a/api.php b/api.php
index 48252d1..c0c1037 100644
--- a/api.php
+++ b/api.php
@@ -599,6 +599,7 @@ function sendTicketMail(string $to, string $subject, string $body, string $inRep
 
     // Jos mailboxilla on SMTP-asetukset, käytä SMTP:tä
     $smtpHost = $mailbox['smtp_host'] ?? '';
+    error_log("MAIL DEBUG: to={$to} smtpHost={$smtpHost} from={$fromEmail} mailbox_keys=" . implode(',', array_keys($mailbox ?? [])));
     if ($smtpHost !== '') {
         return sendViaSMTP($to, $subject, $body, $fromEmail, $fromName, $inReplyTo, $references, $mailbox, $cc);
     }
@@ -618,6 +619,9 @@ function sendTicketMail(string $to, string $subject, string $body, string $inRep
     return mail($to, $subject, $body, $headers, '-f ' . $fromEmail);
 }
 
+/** @var string|null Viimeisin SMTP-virhe (palautetaan frontendille) */
+$GLOBALS['smtp_last_error'] = null;
+
 function sendViaSMTP(string $to, string $subject, string $body, string $fromEmail, string $fromName, string $inReplyTo, string $references, array $mailbox, string $cc): bool {
     $host = $mailbox['smtp_host'];
     $port = (int)($mailbox['smtp_port'] ?? 587);
@@ -628,6 +632,14 @@ function sendViaSMTP(string $to, string $subject, string $body, string $fromEmai
     $timeout = 15;
     $errno = 0; $errstr = '';
 
+    $fail = function(string $step, string $detail) use (&$fp) {
+        $msg = "SMTP $step: $detail";
+        error_log($msg);
+        $GLOBALS['smtp_last_error'] = $msg;
+        if (isset($fp) && $fp) fclose($fp);
+        return false;
+    };
+
     // Yhteys
     if ($encryption === 'ssl') {
         $fp = @stream_socket_client("ssl://{$host}:{$port}", $errno, $errstr, $timeout);
@@ -635,13 +647,12 @@ function sendViaSMTP(string $to, string $subject, string $body, string $fromEmai
         $fp = @stream_socket_client("tcp://{$host}:{$port}", $errno, $errstr, $timeout);
     }
     if (!$fp) {
-        error_log("SMTP connect failed: {$errstr} ({$errno})");
-        return false;
+        return $fail('connect', "{$errstr} ({$errno}) — host={$host}:{$port} enc={$encryption}");
     }
     stream_set_timeout($fp, $timeout);
 
     $resp = fgets($fp, 512);
-    if (substr($resp, 0, 3) !== '220') { fclose($fp); error_log("SMTP banner: $resp"); return false; }
+    if (substr($resp, 0, 3) !== '220') return $fail('banner', trim($resp));
 
     // EHLO
     fwrite($fp, "EHLO " . gethostname() . "\r\n");
@@ -655,9 +666,9 @@ function sendViaSMTP(string $to, string $subject, string $body, string $fromEmai
     if ($encryption === 'tls') {
         fwrite($fp, "STARTTLS\r\n");
         $resp = fgets($fp, 512);
-        if (substr($resp, 0, 3) !== '220') { fclose($fp); error_log("SMTP STARTTLS: $resp"); return false; }
-        $crypto = stream_socket_enable_crypto($fp, true, STREAM_CRYPTO_METHOD_TLSv1_2_CLIENT | STREAM_CRYPTO_METHOD_TLSv1_3_CLIENT);
-        if (!$crypto) { fclose($fp); error_log("SMTP TLS negotiation failed"); return false; }
+        if (substr($resp, 0, 3) !== '220') return $fail('STARTTLS', trim($resp));
+        $crypto = @stream_socket_enable_crypto($fp, true, STREAM_CRYPTO_METHOD_TLSv1_2_CLIENT | STREAM_CRYPTO_METHOD_TLSv1_3_CLIENT);
+        if (!$crypto) return $fail('TLS', 'TLS negotiation failed');
         // EHLO uudelleen TLS:n jälkeen
         fwrite($fp, "EHLO " . gethostname() . "\r\n");
         while ($line = fgets($fp, 512)) {
@@ -669,19 +680,19 @@ function sendViaSMTP(string $to, string $subject, string $body, string $fromEmai
     if ($user !== '') {
         fwrite($fp, "AUTH LOGIN\r\n");
         $resp = fgets($fp, 512);
-        if (substr($resp, 0, 3) !== '334') { fclose($fp); error_log("SMTP AUTH: $resp"); return false; }
+        if (substr($resp, 0, 3) !== '334') return $fail('AUTH', trim($resp));
         fwrite($fp, base64_encode($user) . "\r\n");
         $resp = fgets($fp, 512);
-        if (substr($resp, 0, 3) !== '334') { fclose($fp); error_log("SMTP AUTH user: $resp"); return false; }
+        if (substr($resp, 0, 3) !== '334') return $fail('AUTH user', trim($resp) . " (user={$user})");
         fwrite($fp, base64_encode($pass) . "\r\n");
         $resp = fgets($fp, 512);
-        if (substr($resp, 0, 3) !== '235') { fclose($fp); error_log("SMTP AUTH pass: $resp"); return false; }
+        if (substr($resp, 0, 3) !== '235') return $fail('AUTH pass', trim($resp));
     }
 
     // MAIL FROM
     fwrite($fp, "MAIL FROM:<{$fromEmail}>\r\n");
     $resp = fgets($fp, 512);
-    if (substr($resp, 0, 3) !== '250') { fclose($fp); error_log("SMTP MAIL FROM: $resp"); return false; }
+    if (substr($resp, 0, 3) !== '250') return $fail('MAIL FROM', trim($resp) . " (from={$fromEmail})");
 
     // RCPT TO
     $allRecipients = array_filter(array_map('trim', explode(',', $to)));
@@ -692,14 +703,14 @@ function sendViaSMTP(string $to, string $subject, string $body, string $fromEmai
         fwrite($fp, "RCPT TO:<{$rcpt}>\r\n");
         $resp = fgets($fp, 512);
         if (substr($resp, 0, 3) !== '250' && substr($resp, 0, 3) !== '251') {
-            fclose($fp); error_log("SMTP RCPT TO: $resp"); return false;
+            return $fail('RCPT TO', trim($resp) . " (rcpt={$rcpt})");
         }
     }
 
     // DATA
     fwrite($fp, "DATA\r\n");
     $resp = fgets($fp, 512);
-    if (substr($resp, 0, 3) !== '354') { fclose($fp); error_log("SMTP DATA: $resp"); return false; }
+    if (substr($resp, 0, 3) !== '354') return $fail('DATA', trim($resp));
 
     // Rakennetaan viesti
     $messageId = '<' . uniqid('msg_', true) . '@' . (explode('@', $fromEmail)[1] ?? 'localhost') . '>';
@@ -722,7 +733,7 @@ function sendViaSMTP(string $to, string $subject, string $body, string $fromEmai
 
     fwrite($fp, $msg);
     $resp = fgets($fp, 512);
-    if (substr($resp, 0, 3) !== '250') { fclose($fp); error_log("SMTP send: $resp"); return false; }
+    if (substr($resp, 0, 3) !== '250') return $fail('send', trim($resp));
 
     // QUIT
     fwrite($fp, "QUIT\r\n");
@@ -2275,7 +2286,9 @@ switch ($action) {
 
                 if (!$sent) {
                     http_response_code(500);
-                    echo json_encode(['error' => 'Sähköpostin lähetys epäonnistui']);
+                    $smtpErr = $GLOBALS['smtp_last_error'] ?? '';
+                    $detail = $smtpErr ? " ({$smtpErr})" : '';
+                    echo json_encode(['error' => "Sähköpostin lähetys epäonnistui{$detail}"]);
                     break 2;
                 }