The study by Holger Ebel, Lutz-Ingo Mielsch, and Stefan Bornholdt examines the topology of e-mail networks, where email addresses serve as nodes and emails as links. Using data from server log files, they find that the network exhibits scale-free link distribution and small-world behavior, similar to other social networks. The degree distribution follows a power law with an exponent of -1.81, and the network contains a giant component of 56,969 nodes. The small-world properties are characterized by a high clustering coefficient and a short average path length. The in-degree and out-degree distributions also show power-law behavior, with the in-degree exponent being -1.49 and the out-degree exponent being -2.03. These findings suggest that e-mail networks facilitate the spread of viruses and information, but also provide opportunities for targeted prevention and marketing strategies. The study highlights the importance of understanding the non-trivial topological features of e-mail networks for both security and communication purposes.The study by Holger Ebel, Lutz-Ingo Mielsch, and Stefan Bornholdt examines the topology of e-mail networks, where email addresses serve as nodes and emails as links. Using data from server log files, they find that the network exhibits scale-free link distribution and small-world behavior, similar to other social networks. The degree distribution follows a power law with an exponent of -1.81, and the network contains a giant component of 56,969 nodes. The small-world properties are characterized by a high clustering coefficient and a short average path length. The in-degree and out-degree distributions also show power-law behavior, with the in-degree exponent being -1.49 and the out-degree exponent being -2.03. These findings suggest that e-mail networks facilitate the spread of viruses and information, but also provide opportunities for targeted prevention and marketing strategies. The study highlights the importance of understanding the non-trivial topological features of e-mail networks for both security and communication purposes.