What Email/Groupware software did they use? (Score 4, Interesting)

What email/groupware software are they using on this Linux/390 machine? Is it some port of Lotus Domino server? I am only aware of Domino running natively on S/390 and on Intel x86 Linux, not on 390 mainframe Linux. Also bear in ming that there is no antivirus vendor supporting Domino on any Linux platform so that makes Domino on any Linux platform rather useless, doesn't it?