A single low-end VPS can technically queue and attempt to send tens of thousands of messages an hour — the server hardware is rarely the bottleneck. What actually limits volume is how receiving mail providers (Gmail, Outlook, Yahoo and others) rate-limit and filter based on your sending IP's history, authentication setup, and complaint rate.
A brand-new IP has no sending history; providers throttle unfamiliar senders until trust is established.
Major providers apply their own per-IP and per-domain sending caps, independent of your server's capability.
Opt-in-only lists with low complaint rates earn higher effective sending limits over time than aggressive, unfiltered lists.
As a general guide (not a guarantee), a properly warmed-up dedicated IP with good authentication (SPF, DKIM, DMARC, matching rDNS) and a clean opt-in list can often send a few thousand emails per day to major providers without major deliverability problems. New IPs should ramp up gradually — sending a small fraction of your target volume in the first days and increasing over roughly 2-4 weeks — rather than sending full volume immediately.
We don't impose an artificial cap on legitimate opt-in sending volume; realistic limits come from IP reputation and receiving-server policy, not our infrastructure.
More RAM and CPU help process a larger queue faster, but they don't override receiving-server rate limits or reputation-based throttling.
Gradually, typically over 2-4 weeks, starting with a small fraction of target volume and increasing as your reputation builds.
Consistent opt-in-only sending, low bounce and complaint rates, and correct SPF/DKIM/DMARC/rDNS configuration.
Dedicated IPv4, open Port 25 and custom rDNS — starting at $4.95/month.
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