Promotional products supplier BEL USA LLC, which does business at DiscountMugs.com and other sites, recently began notifying customers who placed an order either online or by phone between March 1, 2013 and July 15, 2013 that their personal information may have been accessed by unauthorized third parties when the site's server was breached.

An independent expert determined that the hackers may have accessed customers' names, addresses, phone numbers, credit or debit card numbers, expiration dates and CVV codes.

"In addition to our investigation, at the same time we began implementing measures to address the situation and retained experts to guide us through our response," company CEO Amin R. Ramjee wrote in the notification letter [PDF]. "Those steps included identifying how personal information was put at risk and implementing changes to address that risk, including replacing the affected server."

No credit protection services are being offered to affected customers -- but they are being provided with a 20 percent off coupon for future orders.