diff --git a/api.php b/api.php
index f26b2c7..ac98c5e 100644
--- a/api.php
+++ b/api.php
@@ -646,8 +646,13 @@ function smtpCode(string $resp): string {
 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);
+    // Fallback-ketju käyttäjälle: smtp_user → imap_user → smtp_from_email
     $user = $mailbox['smtp_user'] ?? '';
+    if ($user === '') $user = $mailbox['imap_user'] ?? '';
+    if ($user === '') $user = $fromEmail;
+    // Fallback salasanalle: smtp_password → imap_password
     $pass = $mailbox['smtp_password'] ?? '';
+    if ($pass === '') $pass = $mailbox['imap_password'] ?? '';
     $encryption = $mailbox['smtp_encryption'] ?? 'tls';
 
     $log = [];  // Debug-loki