如果您有 1 或 2 个用户 MAX，您可以将它们存储在 app.config 或 reg 文件中，但如果您认为会有更多，那么DB将是***的选择.从 SQL 服务器获取它们几乎没有任何成本.另外，看看这个:在注册表中存储和加密 SMTP 凭据

if you have 1 or 2 user MAX you can store them in the app.config or maybe in the reg file but if you think you will have more, then the DB will be the best choice. It cost almost nothing to get them from a SQL server.Also, take a look at this : Storing and encrypting SMTP credentials in the registry