The British comedian confessed the pair first bonded after they penned a song together - entitled `Pug-Nosed Face` - and then began sending emails back and forth.
He explained: "I`ve written a song with him - it was called `Pug-Nosed Face` and it was about me! I sent him the lyrics and I was talking to him on the phone and I was going, `If you could do something really retro like `Life on Mars`?` and he went, `Oh sure, I-ll just knock off a `Life on Mars` for you then shall I?- It was great!
"Later he must have got my email and he said, -I watched `The Office`. It was funny. I laughed. What do I do now?- and we sort of became pen pals."
Ricky also admitted he has even been sending the legendary star abusive emails.
He added to Magic 105.4 radio station: "I remember I sent him an email on his 57th birthday and I said, `57! Isn`t it about time you got a proper job? RickyGervais, 42, comedian.` And he wrote back, `I have a proper job. DavidBowie, 57, rock god`."
The full interview takes place on November 28 on British station Magic 105.4.