OpenPop.NET
Install-Package OpenPop.NET
★.NET接收邮件下载邮件附件——openpop.net★
https://www.cnblogs.com/ZJ199012/p/9070413.html
使用开源opensmtp，openpop发送和接收邮件
https://www.iteye.com/blog/370371029-qq-com-2086924
★Microsoft.ace.oledb.12.0 没有在本机注册★
https://blog.csdn.net/shylx123/article/details/78881621
服务器问题处理
1，Windows Server 2008： 搭建SMTP服务器、配置Outlook、收发邮件
https://blog.csdn.net/qcyfred/article/details/80710094
2，Windows Server 2008 R2架设SMTP服务器发送邮件
https://jingyan.baidu.com/article/363872ec0d3be86e4ba16fdf.html
原文：https://www.cnblogs.com/suntanyong88/p/11905812.html