This design presents a reasonably secure system; as long as each voting user has one and only one acceptable E-mail account, there is reasonable assurance that users could not vote twice.

这种设计可以得到一个比较安全的系统；条件是每个投票的用户都有且只有一个可以接受的电子邮件帐号，这样就可以保证每个用户都不会投两次票。

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Once you understand those basic costs of outages, you next need to determine the acceptable total yearly cost of downtime a a "i."e. how much business or productivity can you afford to lose each year?

一旦您理解了这些问题的基本成本，下一步您需要确定的是每年可接受的故障成本——即每年您可能损失多少业务或生产量？

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You could further tighten the system by modifying the validation method voter_is_okay within the DraftBallot class to consult a list of acceptable E-mail addresses.

您可以通过修改draftballot类中的验证方法voter_is_okay来加强这种限制，使其在进行验证时参考一个可接受的电子邮件地址。

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Surveys also showed users were becoming more tolerant of spam, seeing it as "an acceptable nuisance rather than a cause for abandoning e-mail".

BBC: NEWS | Technology | US 'winning war' on e-mail spam

Of course one could try to look at a number of acceptable stocks that meet set criteria, e.g.

FORBES: Optional Opportunity