/// <summary>
/// Initializes a new instance of the <see cref="MailService"/> class.
/// Init service use token.
/// </summary>
/// <param name="token">access token.</param>
/// <returns>Mail service itself.</returns>
public async Task <IMailService> InitAsync(string token)
{
httpClient = ServiceHelper.GetHttpClient(token);
graphServiceClient = ServiceHelper.GetAuthenticatedClient(token);
return(await Task.FromResult(this));
}