One of the really nice features about e-mails is that they allow us to send files as attachments to other users. This is a very good thing. If I'm working with a colleague and want to send him an image file or a word file, I can do so very quickly and easily, without having to fax it to him. This saves onlong distance bills and printing costs. It also, however, presents a problem, because attachments can take a long time download. For those of us who pay by the hour for Internet service, unwanted attachments can be quite costly and time-consumiung. I once had someone send mefifteen large image files, and it tied up my computer for 20 minutes just to download one of them. So, in short, if you're going to send an attachment, get permission first.

以下是我自己翻译的内容：
电子邮件一个非常好的特征就是让我们能够发送文件像是附件给其他的用户。这点非常的好。如果我正和我的同事工作，并且想发给他一个图片文件又或者是文字文档，我可以非常快速和简单的做到这一点，而不必去把这些文件传真给他。这样做节省了大笔的财力和打印的支出。但这样也存在问题，因为附件要话很长的时间来下载。对我们这些按小时上网的人，不想要附件的人来说，这是相当费钱和费时的。曾经有一个人给我传了15个大的图片文件，而我花了20分钟仅仅才下载了其中的一个文件。因此，简单的来说，如果你想要发送附件的话，最好先得到对方的允许。