Spam levels have finally bounced back to levels seen prior to the shutdown of notorious Web hosting provider McColo in November of last year, at least from the vantage point of Postini, Google’s e-mail security provider. Postini said its measure of the seven-day average spam volume didn’t return to pre-McColo measurements until March 23. “What we have seen in Q1 is a slow but steady return to before-McColo” spam levels, said Adam Swidler, Postini’s product marketing manager. Still, just as some anti-spam hardware and software vendors saw anywhere from a 50 percent to 75 percent drop in spam after McColo was shuttered, depending on their view, I should note that some e-mail security providers cited a resumption of pre-McColo spam levels as early as December. As far as spam trends in first quarter 2009, the spammers appear to be dusting off tried-and-true infection and distribution methods, Postini reports. Virus-laden e-mail