diff --git a/backend/api/v1/modules/crm/quotes/pdf_service.py b/backend/api/v1/modules/crm/quotes/pdf_service.py
index 2225090..4fc9026 100644
--- a/backend/api/v1/modules/crm/quotes/pdf_service.py
+++ b/backend/api/v1/modules/crm/quotes/pdf_service.py
@@ -210,19 +210,25 @@ async def send_quote_email(
     part.add_header("Content-Disposition", f'attachment; filename="cotizacion-{ref}.pdf"')
     msg.attach(part)
 
+    if not (cfg.SMTP_USER and cfg.SMTP_PASSWORD):
+        raise HTTPException(status_code=503, detail="El correo saliente (SMTP) no está configurado en el servidor.")
     ctx = ssl.create_default_context()
     ctx.check_hostname = False
     ctx.verify_mode = ssl.CERT_NONE
     try:
-        if cfg.SMTP_PORT == 465:
-            async with aiosmtplib.SMTP(hostname=cfg.SMTP_HOST, port=cfg.SMTP_PORT, use_tls=True, tls_context=ctx) as smtp:
-                await smtp.login(cfg.SMTP_USER, cfg.SMTP_PASSWORD)
-                await smtp.send_message(msg)
-        else:
-            async with aiosmtplib.SMTP(hostname=cfg.SMTP_HOST, port=cfg.SMTP_PORT, tls_context=ctx) as smtp:
-                await smtp.starttls(tls_context=ctx)
-                await smtp.login(cfg.SMTP_USER, cfg.SMTP_PASSWORD)
-                await smtp.send_message(msg)
+        # Puerto 465 = SSL implícito; los demás (587/2525/…) = STARTTLS.
+        await aiosmtplib.send(
+            msg,
+            hostname=cfg.SMTP_HOST,
+            port=cfg.SMTP_PORT,
+            username=cfg.SMTP_USER,
+            password=cfg.SMTP_PASSWORD,
+            use_tls=(cfg.SMTP_PORT == 465),
+            start_tls=(cfg.SMTP_PORT != 465),
+            tls_context=ctx,
+            validate_certs=False,
+            timeout=30,
+        )
     except Exception as exc:
         logger.error("Error enviando cotización %s: %s", quote_id, exc)
         raise HTTPException(status_code=502, detail=f"No se pudo enviar el correo: {exc}")