Apologies if I missed this announcement made the list already.
I was surprised to find these survey numbers tonight. Given Exim is no longer a default install on many distros, I was surprised to find that Exim constitutes 53% of the mail servers on the internet. The numbers are a little skewed given some banners didn't report their mail server, but it's still impressive.
http://www.securityspace.com/s_survey/data/man.201510/mxsurvey.html
Less impressive is that only 20% of exim servers are up to date :(
Todd Rinaldo