IBM now offers support for OS X 10.8.x Mountain Lion.
There are two possibilities for already installed clients:
– Interim Fix 1 for 8.5.3 Fixpack 2
– 8.5.3 Fixpack 3
For new installations, use the new installer:
– Notes 8.5.3 Slipstream (Part No: CIBF8EN)
Follow this link for more information and download:
Supportability Q&A about Lotus Notes and OS X 10.8.x