Direct mail's key strength is the "mail moment" - 97% of consumers open their mailbox every day but only receive 2 direct mail pieces per week, so it has a high chance of being opened. Email checking is less frequent than opening physical mail. Direct mail represents 10.3% of gross media spending in Belgium. The challenges of email include spam, gaining attention, and multiple addresses versus the challenges of direct mail being cost, flexibility, and keeping databases updated. When measuring email campaigns, metrics include open rates, clickthroughs, and interactions versus direct mail where cost and targeting unique individuals are strengths.