public void SmtpDate_TimeSpanToOffset_ShouldConvertCorrectly()
{
var smtpDt = new SmtpDateTime(DateTime.Now);
TimeSpan timeZone = TimeZoneInfo.Utc.GetUtcOffset(DateTime.Now);
string timeZoneToString = timeZone.ToString();
string result = smtpDt.TimeSpanToOffset(timeZone);
Assert.Equal("+0000", result);
}