Were King Louis XI's Mail Carriers the First Flask Drinkers?

They say that on June 19, 1461, King Louis XI created the first ever postal service, by creating royal postal roads to deliver official parcels and packages at higher speeds. If 1464 was the first year that mail carriers started work, I’d bet 100 Francs that France started selling a lot of flasks around that same time.
Imagine having to be a French mail carrier in 1464? This would have been the first time that mail was ever delivered. That whole “don’t shoot the messenger” quote? I reckon it started here. This is because in the olden times, it used to be that a messenger was more of a representative of the message or package he or she was delivering, whether it was a scroll, food, or someone's head. 
With the introduction of mail, however, mail carriers started to shift from representatives of the item they were delivering and more toward neutral delivery messengers. Of course, there was probably a rough transition period, as the receivers of packages likely didn't quite catch on as quickly. As a result, mail carriers probably had to start dealing with a lot of unhappy customers.
I could just imagine this heated conversation taking place:
“You delivered me an Extra Large robe?? I distinctly asked for a Medium! Now how am I going to attend the masquerade and look normal! I want my Francs back and I want them back right now!”.
“Now, now, I'm just the messenger – here to deliver mail and be on my way!, says the mail carrier as he nervously chuckles, runs back into his horse & carriage, and likely takes a swig from his flask.
Can you imagine the pressures that mailmen dealt with on the backroads of France in 1464? It was probably a very stressful job!
That is why I have no doubt that flasks were definitely purchased, used, and abused by many French mailmen in the mid to late 1400’s.
The question is, what sort of flasks did they carry on route? Because drinking and driving rules were probably lax back then, there was probably no issue with the amount of alcohol one consumed.
I reckon that the French mailmen carried pretty big flasks back then. What, you thought that 64 oz flasks were big? Considering that they probably had a lot of spare room in their horse and carriage, mailmen probably had pouch flasks that carried upwards of 100 oz.
The content of the flasks is likely not a matter of debate: Sure the French loved wine, but these mailmen needed liquid courage and relief at a much faster pace than wine. Their flasks were definitely filled with unfiltered whiskey: harsh, strong, but gets the job done. And the one alcohol they stayed away from was probably Absynthe. Because no one wants a hallucinating mailman.