Against the backdrop of a deteriorating security environment and an increasingly digitalised society, the study demonstrates that physical mail remains a critical component of the total defence system, particularly for legal certainty, public administration, the dissemination of societal information, medical flows, and the supply of spare parts. At the same time, the study finds that actors vital to society generally lack a consolidated understanding of their organisations' overall need for physical mail items in peacetime, which complicates the work of setting priorities in the event of heightened preparedness and, ultimately, war. Through interviews, workshops, and a case study of Ukraine, both vulnerabilities and areas of development are identified. The findings indicate that postal operators may assume an expanded role in wartime, for example in humanitarian deliveries, pharmaceutical distribution, and financial services. The study also highlights the need for clearer mandates, improved coordination between stakeholders, and the establishment of a national prioritisation framework for postal flows during crises. Overall, postal services emerge as a strategic, yet currently insufficiently systematised, resource within Sweden's total defence.