Also, I love the idea of a DIY Bitmessage-Mail-gateway on my own hardware. Is there anything out there already?
All the pieces exist if you know how to put them together.
If you're running your own mail server, then you can run Bitmessage in daemon mode and use
bmwrapper to add a POP/SMTP interface that your stack can interface with.
Thanks for the pointer, noted down!
Offline System (Armory only if I recall right...)
The offline system is completely uncritical. It doesn't need bitcoind nor the Armory blockchain, so 100mb free HDD space is enough. CPU and memory wise, a Raspberry Pi is already sufficient. This means that *any* computer you are able to install a recent OS on will be fine with offline Armory. I highly suggest Linux for this.
It got much, much better with the online system too. Before, you needed around 8 gig memory. Now a "normal computer" is fine. Others will chime in what this means in detail (more than 50gb HDD for example).
Ente
Ty for that, I know shit about linux aside from my limited experience with my cloud VPS.
So that said, it would be I guess as you said, at least for offline, any old laptop I can get my hands on with at least one USB port running XP, Vista or I guess 7. However XP is the only OS I have a copy of.
Yep, anything with USB should do.
I'd really suggest you to give Linux a try. Use a Ubuntu Live-CD for example, if you don't like it, remove the CD and use windows as before (well, backup your wallet, right? heh)
You will only be using Armory anyway. Armory (and firefox and openoffice and thunderbird etc) look all the same, no matter if on windows or Linux.
Linux will be more robust, and runs better on slower hardware than comparably new windows versions.
You'll get plenty of help should you get stuck.
Ente