Despite the wide range of special characters which are technically valid, organisations, mail services, mail servers and mail clients in practice often do not accept all of them.
尽管范围广泛的特殊字符在技术上是有效的，但在实践中，组织、邮件服务、邮件服务器和邮件客户端，往往并不能接受所有这些字符。