Apparently, between May and December of last year, there were 2,398,928 publicly reachable Exim servers listening on IPv4 port 25 on the Internet, or 17.7%. More than any other identifiable server type.
http://internetcensus2012.bitbucket.org/serviceprobes/25_TCP_product.html
Even more impressively, 40.3% of hosts listening on port 587 (1,778,270) are running Exim.
http://internetcensus2012.bitbucket.org/serviceprobes/587_TCP_product.html
Version breakdowns are also available. 4.77 is overwhelmingly in the majority.
--
Ian Eiloart
http://twitter.com/IanEiloart
07876-123-969
--
Ian Eiloart
Postmaster, University of Sussex
+44 (0) 1273 87-3148
