Some information about this already available here. Here is the account of how I got it working on Ubuntu 16.04 64bit LTS system:
Step 1:
Please download the following two Lotus Notes packages from the following links
1. ibm-notes-9.0.i586.deb
2. ibm-sametime-9.0.i586.deb
Step 2:
You might need to add some repository to install 32-bit libraries. So add the following repository into your "software sources"
deb http://old-releases.ubuntu.com/ubuntu/ raring main restricted universe multiverse
Now do the following:
$ sudo dpkg --add-architecture i386
$ sudo apt-get update
Step 3:
Now install the following packages:
$ sudo apt-get install libart-2.0-2:i386 libasound2:i386 libatk1.0-0:i386 libavahi-client3:i386 libavahi-common3:i386 libavahi-glib1:i386 libbonobo2-0:i386 libbonoboui2-0:i386 libc6:i386 libcairo2:i386 libcanberra0:i386 libcomerr2:i386 libcups2:i386 libdbus-1-3:i386 libdbus-glib-1-2:i386 libexpat1:i386 libffi6:i386 libfontconfig1:i386 libfreetype6:i386 libgail18:i386 libgcc1:i386 libgconf-2-4:i386 libgdk-pixbuf2.0-0:i386 libglib2.0-0:i386 libgnome2-0:i386 libgnomecanvas2-0:i386 libgnome-keyring0:i386 libgnomeui-0:i386 libgnomevfs2-0:i386 libgpg-error0:i386 libgssapi-krb5-2:i386 libgtk2.0-0:i386 libhunspell-1.3-0:i386 libice6:i386 libjpeg62:i386 libk5crypto3:i386 libkeyutils1:i386 libkrb5-3:i386 libkrb5support0:i386 libltdl7:i386 libnspr4:i386 libnspr4-0d:i386 libnss3:i386 libnss3-1d:i386 libogg0:i386 liborbit2:i386 libp11-kit0:i386 libpam0g:i386 libpango1.0-0:i386 libpcre3:i386 libpixman-1-0:i386 libpng12-0:i386 libpopt0:i386 libselinux1:i386 libsm6:i386 libstdc++6:i386 libtasn1-6:i386 libtdb1:i386 libuuid1:i386 libvorbis0a:i386 libvorbisfile3:i386 libx11-6:i386 libxau6:i386 libxcb1:i386 libxcb-render0:i386 libxcb-shm0:i386 libxcomposite1:i386 libxcursor1:i386 libxdamage1:i386 libxdmcp6:i386 libxext6:i386 libxfixes3:i386 libxft2:i386 libxi6:i386 libxinerama1:i386 libxml2:i386 libxrandr2:i386 libxrender1:i386 libxss1:i386 libxt6:i386 libxtst6:i386 zlib1g:i386 unity-gtk2-module:i386 libcanberra-gtk-module:i386 libxss1:i386 gtk2-engines-murrine:i386 p11-kit-modules:i386 libp11-kit-gnome-keyring:i386 ttf-xfree86-nonfree gdb iproute2 libgconf2-4:i386 libxkbfile1:i386 lib32ncurses5 lib32z1 libidl-2-0:i386 libpangox-1.0-0:i386 libpangoxft-1.0-0:i386 libasound2-plugins:i386 libgail-common:i386 overlay-scrollbar-gtk2 libgnome-desktop-3-12:i386 libatk-adaptor:i386 libgcrypt20:i386 libgnutls30:i386
You also need to install following packages:
$ sudo apt-get update; sudo apt-get install libgnomeprint2.2-0:i386 libgnomeprintui2.2-0:i386 libbonobo2-0:i386 libbonoboui2-0:i386 libgconf2-4:i386 libgnome-desktop-2-17:i386 libgnomevfs2-bin:i386 libgnomeui-0:i386 libjpeg62:i386 libpam0g:i386 libxkbfile1:i386 ttf-xfree86-nonfree t1-xfree86-nonfree -y
Step 4: Install the notes packages
$ sudo dpkg -i ibm-notes-9.0.i586.deb
$ sudo dpkg -i ibm-sametime-9.0.i586.deb
That's all. It worked for me.
Edit: Thanks to Sunil for his comments.