hMail默认DB是MSSQLServerCompact3.5根据业务需要修改为MySQL1.-下载安装MySQL：https://dev.mysql.com/downloads/mysql/需要先安装VSC++Redistributable:https://learn.microsoft.com/en-us/cpp/windows/latest-supported-vc-redist?view=msvc-170#visual-studio-2015-2017-