"Electronic Notification", or "Electronic Shipping Info Received" means that the vendor has notified the shipper about a pending package. It doesn't mean they have delivered it to the post office/shipper. lol. I figured that out after experiencing delays like you mention.
And it depends on the post office/shipper how fast they acknowledge receipt too.
So the vendor printed a shipping label for you on Monday. Probably didn't get to mixing it up until after shipping hours Monday, or on Tuesday, then dropped it off. You got additional information when you checked on Wednesday. It's on it's way to you. Sometimes USPS doesn't deliver "special packages" on Saturday either. lol.
Also depends on the time of day you place an order...they may not be able to get the order out on the same day. And the fact that they custom mix, like blonde said, can add delays. So it varies. I wouldn't be too awfully upset unless it went beyond that. If I placed an order on a Monday evening and it didn't hit the PO until Thursday or Friday, I might be disappointed.
Welcome to vape-mail.
P.S. You ordered Sunday night. Well... they custom mix... may even had to wait for supplies or they got busy or whatever. It's a little slower than average IMO, but not that bad. If it went beyond that, or is aways 3 days, I'd probably find another vendor. But that's me. If you like the juice, just order earlier. I suppose as a business, they are allowed to set their own expectations as to how long it takes. Then there's the competition factor...others may do it faster. Who knows. For all I know, they have the world's greatest juice...but take an extra day.