As for spam, ISPs (including mail service providers) could limit their users to, say, 100 e-mails a day; for more, you have to pay or at least post a security bond, or pass some good behavior test.

对于垃圾邮件，网络服务商(包括邮件服务商)应该对用户有所限制，比如说每天只能发一百封邮件，更进一步说，你得付费，或至少发布安全债券，或通过一个好的行为测试才行。

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