"This method can be very controversial since it traditionally creates low opt-in rates, but I would argue it's actually more beneficial for several reasons," Kolbenschlag wrote.
Watson of Spamhaus wrote that the organization did tweak its systems around the holidays last year, which resulted in some of the blocking. But the adjustments only brought to light ongoing spam issues and "do not create those spam problems," he wrote.
Send news tips and comments to email@example.com. Follow me on Twitter: @jeremy_kirk