It would be nice if the Brazilian government adopted and helped to improve an existing open source solution (may I recommend Kolab?) instead of falling prey to NIH.
As others have mentioned, PIM is very difficult and if it's done wrong, you end up with metadata leaking across the Internet, security flaws, etc.
If the real issue is with the inability to see the source then open source is better than "Brazilian government"-proprietary, as the NSA could simply hack the source code repository, CIA could plant an insider, the list goes on. You could have someone whose job is to audit the integrity of the archive, but who watches the watchers? With open source the problem is simpler: everyone can watch the source code archive.
As others have mentioned, PIM is very difficult and if it's done wrong, you end up with metadata leaking across the Internet, security flaws, etc.
If the real issue is with the inability to see the source then open source is better than "Brazilian government"-proprietary, as the NSA could simply hack the source code repository, CIA could plant an insider, the list goes on. You could have someone whose job is to audit the integrity of the archive, but who watches the watchers? With open source the problem is simpler: everyone can watch the source code archive.