A: It depends on the Namecheap VPS specs. Also, the specs we recommend are so customers have a good experience, I've seen people talking about running it on a $6 VPS with barely any hardware but that's going to be suboptimal in many ways and I don't want people to blame the software or perceive it as being slow. It's going to run poorly with 1GB of RAM and spend a lot of time in swap, if the person running the VPS even has swap enabled in the first place, and if they don't you may actually just run out of memory and crash.

The VPS recs are based on what we know first-hand runs perfectly and which most customers are now also using.

The difference between Velocity MTA and using something like Mailgun is explained in this post:

https://docs.emaildelivery.com/docs/reply-to-elmejor

Basically, when you use an ESP you're on a shared IP pool with an established sender reputation so your mail is generally delivered without a problem.

When you use Velocity MTA it's the same as being on a dedicated IP at an ESP, which means you have zero established sender reputation, you have to start off very slow (think 10-20 messages on day one) and do a long and careful warmup to establish your reputation with the mailbox providers like Gmail, Yahoo, Outlook, iCloud, etc.

So you can send unlimited emails in regards to your software not having any limitations on what you can send and where you can send it, but in a practical sense, the mail is limited by what the mailbox providers are willing to accept from your IP(s) and domain(s), and they're going to accept more mail from an establish ESP's IP pool than your Velocity MTA IPs, at least at first.