"Do not expect any privacy by using any commercial communication platform or solution."
I'd say don't expect privacy - end of story. Commercial platforms as well as "secure" ones that use encryption are still liable to surveillance and confiscation of data. I think, when you're on the net, your data is always being saved somewhere (since that's usually a big revenue model, and also simply a software development practice for analyzing users/software bugs, etc), even if your connection is secure. The only way I could see that anything could purport to be "truly" absolute on your privacy would be that they - like DuckDuckGo for example - simply would not save any data, period. If you have that plus encryption, you still have the problem of your ISP, which is semi-mitigated by Tor-based solutions.
It depends on the type of "privacy" you need, but your ISP isn't a threat if you're using good crypto, unless you're just worried about connecting to marked IPs, in which case a proxy, VPN, or asking your collaborator to open up a new IP are all viable resolutions.
I'd say don't expect privacy - end of story. Commercial platforms as well as "secure" ones that use encryption are still liable to surveillance and confiscation of data. I think, when you're on the net, your data is always being saved somewhere (since that's usually a big revenue model, and also simply a software development practice for analyzing users/software bugs, etc), even if your connection is secure. The only way I could see that anything could purport to be "truly" absolute on your privacy would be that they - like DuckDuckGo for example - simply would not save any data, period. If you have that plus encryption, you still have the problem of your ISP, which is semi-mitigated by Tor-based solutions.