I think it's fine to mention that v5.91 is an old version in the context of this thread since it does not support UTF-8. Apart from that, anyone using an older version of mIRC may be open to remote exploits which means that their computer can be compromised with serious implications for them and others. So if an older version is mentioned in a thread, I usually point out that it should not be used for security reasons, regardless of the topic thread, and that users should upgrade to v6.35 or v7.19.
