MailKit帮助类
https://github.com/jstedfast/MailKit
https://github.com/jstedfast/MimeKit
https://www.cnblogs.com/pengze0902/p/6562447.html
public class EmailHelp
{
/// <summary>
1. Desktop selection|Other|Text Mode.2. Change the Installation source:[url]ftp://mirror.pacific.net.au/linux/opensuse/distribution/SL-10.1/inst-source/[/url]3.Install the followwing packagespostfix d
