import * as XLSX from 'xlsx';
export declare function checkZaloSendable(lastMessageAt: Date | null): {
    canSend: boolean;
    reason: string;
} | {
    canSend: boolean;
    reason: null;
};
export declare function formatZaloDateFromExcel(cell: XLSX.CellObject | undefined): string;
export declare function isLikelyExcelDate(n: number): boolean;