I recently transferred a domain from an old registrar to Namecheap.
There was a line that said something along the lines of: "You can setup email forwarding for free but you won't be able to send emails from the address", which kind of confused me at the time, so I added email to my order for a fee.
But I already had a Google Apps account and I use Gmail. After the transfer completed I updated my DNS to include Gmail's MX records, and it all still seems to be working, but I'm not sure if Namecheap's service is part of what's making it work or completely unrelated.
In the mail section at Namecheap there is an alert that says to add their MX records and an SPF record which leads me to believe that their service isn't even doing anything yet; and if Gmail is still working then I believe I can cancel the Namecheap service.
I just need some reaffirmation that this is how it works because this is for a business and I don't want to miss out on any customers. MX records are all I need to to send and receive emails through Gmail?
With Google Apps, there's nothing you need on your DNS when you're talking about sending. With receiving, that's where you'll need the MX records. More information about how MX records work can be found here.
You will need to confirm with Namecheap regarding that specific service you signed up for to check for any consequences of cancelling it (e.g. you can't set up MX records without it). It's likely just their own mail service which you don't need b/c you've got Apps.