Weird "ghost spam" testing addresses
A wave of strange emails with strings of numbers as their only message are most likely a spammer's or hacker's test of his mailing list, several security companies concluded Thursday, and may presage a junk mail campaign or a malware attack.
The messages, which Panda Software characterised as "ghost mail," are unusual in that the send and from fields are the recipient's own address, that the subject heading is a number - 455, 557, 56757, 586876, or 1545453 - and the message body is a mix of HTML and apparently random numbers.
Unlike most malicious mail or spam, these do not include a file attachment (the usual way email is used to deliver worms or trojan horses), nor do they include an embedded link, as do phishing messages.