Postini discovered seven billion spam messages worldwide in November, up from 2.5 billion in June.
"Email systems are overloaded or melting down trying to keep up with all the spam," Dan Druker, a vice president at Postini told Reuters.
The volume of spam in Britain alone has increased by 50 per cent over the last two months, security firm SurfControl claims.
However, some experts argue that technology will not defeat spam. The only way to contain the problem is for people to stop responding to it, Trend Micro's Dave Rand told the news service.
"The products they are selling by spam are exactly the same products they sold in the Middle Ages," Rand said.
"This really is a human problem, not a computer problem."