[tom1337]

Also, the magnet text is not visible:

style="position: absolute; left: -9999px; top:-9999px;display: none"

maybe they try to warm up those emails to use them for other "campaigns" later on...

[mike-cardwell]

The text is added to get around bayesian filters. The spammer doesn't want the text to be displayed to the end user though typically.

[autoexec]

A smart bayesian filter would catch email with invisible text. Legitimate email shouldn't have any, but I have seen it more than once in spam