Yet another phishing scam, claiming to be from paypal and about problems with my account. Only this one had, at the very beginning of the subject line, the tag "[spam]".
Your ISP may have started running SpamAssassin or a similar package. That program's default configuration seems to be to identify potential spam and simply label it as such in the subject line.
From:
no subject
And they say there's no truth in advertising...
From:
The sender may not have put that there ...