Our mail server enables an anti-spam technique called greylisting (as well as others) which helps prevents upwards of 90% of all spam from entering your POP email inbox. The only downside to greylisting is that it can delay emails from being received by usually 10 to 20 minutes but only affects the first email being sent from the same sender once per day.
Grelisting can be disabled. To do so, simply log-in to your webmail account at http://webmail.bigblackbag.com and then click the disable greylising option in the Settings section.