The reason, the MSP says, is that one of the target groups the spammers have in mind is students returning after the summer break.
"It's a pattern we've seen in previous years, but this September does look as if it will be the largest increase yet," said Diego d'Ambra, SoftScan's CTO.
"Although we cannot predict with absolute certainty that this tendency for an increase in spam in September will continue, there are some strong indications," he said.
According to d'Ambra, spammers are constantly improving their methods and are developing new types of spam to get by the filters.
"Last autumn it was image spam, this year they've switched their attention to document and e-card spam," he explained.
One of the groups that SoftScan believes spammers will be targeting is the large number of students returning to educational institutions after the summer break, many of whom unwittingly bring in laptops already infected.
The laptops then provide the spammers with a potential back door to large and fast network resources to continue distributing their malware.
So next time you're emptying out your spam folder, you'll know why it's so large. You won't be happy, but at least you'll know why...