If you can only find a generic webform, no company name, telephone number, email address, postal address -- that's it, case closed.

如果你只能找到一般性的网路表单，没有公司名、电话号码、 电子邮件地址、实体地址──那就对了，结案。

This item is the postal address of the author of the letter.

这是这封信作者的邮政地址。

For example, 'I am writing to ask for more information about your event', or 'I am writing to inform you of my new postal address'.

例如，“我写信是想了解关于您举办的活动的详细信息”，或者“我写信是想通知您我新的通讯地址。”

It involves the full name of the intended recipient of the letter and that person's postal address.

它包括信件收件人的全名和该人的邮政地址。