SL6 uses OpenSSL v1.0.1, which is no longer supported by OpenSSL ( https://www.openssl.org/policies/releasestrat.html ). v1.0.2 which may be a drop in replacement is supported until the end of 2019. https://access.redhat.com/solutions/1530413 explains Red Hat's position on this, but it can only be read by those with a Red Hat contract. Could SL make a similar statement which is available to anyone who has access to SL ? I'm particularly asking since I'm trying to build the latest exim, which does not support openssl v1.0.1 https://lists.exim.org/lurker/message/20170131.025153.592b38db.en.html As we are into 2017, the oldest OpenSSL supported by the OpenSSL project is 1.0.2, so that is now the oldest version which the Exim Maintainers formally "support" for Exim. As of yet, I do not believe that any changes have been merged which would break support for older OpenSSL, but you are on your own if you try to use such. I can of course build a local OpenSSL v1.0.2 for exim, but if there were a system version it would be simpler for me. Thanks, -- Andrew C Aitchison