How Spammers Verify Your E-mail Address

This Apple Knowledge Base article explains how spammers can verify your e-mail address by using HTML e-mails. It suggests strategies you can use to avoid this, using the built-in OS X Mail client as an example, but keeping it general enough to apply to any HTML-capable e-mail client.

This problem suggests a couple of things:

1) If this practice continues, an increasing number of users will turn HTML rendering off entirely. This means that HTML-only e-mail will be unreadable by them.

2) At a minimum, you should ALWAYS include a text-only version of any HTML e-mail that goes out if you must send HTML.