fix version 1

module/base/sender/internal/logic/mail/send.go

@@ -27,8 +27,11 @@ func Send(ctx context.Context, in *pb.SendMailRequest) (reply *pb.SendMailReply,
 		return nil, errcode.ErrInvalidArgument
 	}
 
-	// 校验配置
+	// 校验配置：聚合部署只配置 default 段时回退到默认邮箱通道配置
 	cfg, ok := config.Spec.SMTP[provider]
+	if !ok || cfg == nil {
+		cfg, ok = config.Spec.SMTP["default"]
+	}
 	if !ok || cfg == nil {
 		return nil, excode.ErrProviderIsNil
 	}