private static List<SignatureDto> GetMailboxesSignatures(List<int> mailboxIds, int tenant, DbManager db)
 {
     var signatureDal = new SignatureDal(db);
     return signatureDal.GetSignatures(mailboxIds, tenant);
 }
 public List<SignatureDto> GetMailboxesSignatures(List<int> mailbox_ids, string user_id, int tenant)
 {
     using (var db = GetDb())
     {
         CheckMailboxesOwnage(mailbox_ids, user_id, tenant, db);
         
         var signature_dal = new SignatureDal(db);
         return signature_dal.GetSignatures(mailbox_ids, tenant);
     }
 }