PowerShell發送郵件（587）

發送html格式郵件（圖檔位于可通路站點上）

發送郵件，正文包含的圖檔位于本地計算機

$smtp.UseDefaultCredentials = $false 要放在SmtpClient.Credentials之前

 If the UseDefaultCredentials property is set to false, then the value set in the Credentials property will be used for the credentials when connecting to the server. If the UseDefaultCredentials property is set to false and the Credentials property has not been set, then mail is sent to the server anonymously.