One rather appalling discussion that I have seen was on an Internet marketing newsletter, where the editor was exulting in this new marketing tool, seeing it as a kind of automatic spam. I am very much afraid that someone will be trying this, and probably very soon. A number of fixes for mail servers and mail filtering systems have been devised very quickly. However, note that not all of these have fully tested or debugged. One version that I saw would trap most of the warning messages about Melissa.
Mail filters can, of course, become problems themselves.
There is a message that is displayed approximately one time in sixty. The exact trigger is if the current system time minute field matches the current system time day of the month field when the virus is run. I'm outta here. Rather ironically, a clue to the identity of the perpetrator may have come from the identification number embedding scheme recently admitted by Microsoft as having been included with Office and Windows 98. Certainly trying to use the global user ID as evidence in court will be interesting, to say the least.