The Tour's internal post office - run by Docapost, a branch of France's national postal service system - reports that whilst Thomas Voeckler is, perhaps unsurprisingly, the local rider receiving most fan mail ahead of Sylvain Chavanel, Alejandro Valverde is currently the leader on the international standings, well ahead of the Frenchman.
Usually it's the top favourites who get the most post. In 2010, Lance Armstrong received the most messages of encouragement - 327, whilst in 2011 Voeckler finished ahead of Andy Schleck and Alberto Contador with 275.
Docapost has been delivering fan mail to the Tour de France riders since 1992 and receives roughly 4,500 letters for the pro's each year. Correspondence can be sent via email or postcards.
This year it is Valverde who is in top spot in what is one test of riders' popularity.
"It's a bit of a surprise, because he's not having a great Tour, but he gets loads of emails and he's ahead by a long way," says Jean Marc Campana - who has run Docapost's Tour post office together with co-worker Sylvain Forre for the last three years.
"Alejandro doesn't get many letters, though - if it wasn't for the emails, though, he'd be a long way back."
The Tour's Post Office, unsurprisingly, is as mobile as the rest of the race. The two Docapost employees operate out of the back of a large lorry parked up for most of the day next to the Tour's press room, which has all sorts of mailing paraphernalia in the back: scales, stamps, postcards (for Tour followers who want to send any correspondence, although there is also a postbox at the Tour's 'village' at each start) and a sorting system with each of the teams' names on its own pigeon hole.
Fans wishing to write to riders can do so via email on www.docapost.com/tourdefrance, which are then printed out and sent on to the teams. For those wishing to send letters, just writing the rider's name and team followed by Tour de France - DOCAPOST and the postcode for the finish town (available on docapost's website) where you want the letter to arrive should see it get there.