How do you think GCHQ get their info
If I knew, I'd have to kill you.
What's your address again ?
Don't worry, only joking, I don't officially know, but I can take a fairly good guess.
To quote Donald R.
There are known knowns; there are things we know we know.
We also know there are known unknowns; that is to say we know there are some things we do not know.
But there are also unknown unknowns – there are things we do not know we don't know.
i.e.
Its likely not as neat and tidy as you may think, hence the previous government's introduction (or rather attempted introduction) of all sorts of legislation and schemes to give them insight into areas that they are a bit grey on at the moment (you know, the "Interception Modernisation Programme", now snappily known as the "Communications Capabilities Development Programme" and all that jazz).
Aaah.... Saab.... the great oracle of the slowly dying protocols.
Who else have you got up on your ward Saab ? Is Mr Banyan VINES still alive ?
And what's the joke about gmail?
Its public knowledge that Google trawl their gmail databases for the purposes of delivering targeted advertising to you based upon the content of the emails you send and receive.
Depending on how you feel about such matters, you may or may not choose to expand the potential purposes of the trawling exercises. I'll leave that one for you to decide.