So how many emails can a VPS send?

More than your reputation will let you deliver. For a plain mail transfer agent the server is almost never the constraint — a modest VPS can hand off far more messages per hour than a new sending IP will be allowed to deliver. The honest answer is that the question has the wrong subject: ask how many your IP reputation and list quality support, because that is the number that binds.

Why will nobody give me a number?

Anyone who does is guessing. The figure depends on your list quality, your content, your authentication, your IP history and the receiving providers your subscribers use. A hosting company knows none of those. Numbers on hosting pages are marketing, not measurement.

How do I work out my own realistic figure?

Start small and let the receiving providers tell you. Send to your most engaged subscribers first, watch deferrals and bounces, and increase volume only while those stay low. Deferrals are the signal that you have reached the current limit for your IP — back off rather than retrying harder.

Does a bigger plan let me send more?

Not in the way the question implies. A bigger plan helps the campaign software — segmenting large lists, building reports, running automation — and it will not persuade Gmail to accept more from a cold IP. Buy capacity for the database, not for the mail server.

How long does IP warm-up take?

Weeks rather than days, and it is a curve rather than a switch. You increase volume gradually while watching deferral and complaint rates, and you send to your most engaged subscribers first because their opens are the positive signal that builds reputation. Rushing it is the most common way people ruin a new address.

Does the software I run change the limit?

It changes how well you can respond to the limit. Postal and PowerMTA are delivery engines that manage queues and retries; PowerMTA in particular gives fine-grained per-domain throttling, which is exactly the control you want at high volume. Campaign software like Mautic or MailWizz does not deliver mail at all.

What is the minimum server for serious sending?

It depends on the software rather than the volume. Postal documents a minimum of 2 CPU cores, 4 GB RAM and 25 GB disk, which is the only hard published figure among the common options. A plain Postfix relay is comfortable on far less.

Would a relay let me send more?

On day one, yes, considerably — a relay lends you an established reputation instead of making you build one. That is the honest case for relaying, and for many senders it is the right call. What you give up is per-message cost and control.

Is Port 25 guaranteed on every plan, or just open?

Both, depending on the range, and the difference is worth knowing before you buy. Outbound Port 25 is open by default on all 16 plans — no ticket, no approval step. On NVMe VPS, Cloud VPS, Classic VPS and VDS it is written into the published plan specification. On it is open because of how the network is run rather than as a documented guarantee. In practice it behaves the same on all of them, but if your business stops when you cannot send, buy the range that puts it in writing.

Sending Volume · Straight Answer

More than your reputation will let you deliver.

Every hosting company publishes a messages-per-hour figure. All of them are invented, because the number depends on your list, your content and your IP history — none of which a host knows. What we can do is explain what actually caps your sending and give you a way to find your own figure.

Reputation is the cap
Rarely the hardware
Warm-up takes weeks
Port 25 open here

What Actually Limits You Find Your Own Number

Messages-per-hour figures we publish

Because we cannot know your list, and neither can anyone else

Bandwidth is never the limit
CPU is almost never the limit
A bigger plan will not warm your IP
A purchased list ends it in one campaign

The Answer, in One Paragraph

For a plain mail transfer agent, the server is almost never what limits your sending. Postfix relaying to the internet spends most of its time waiting on remote servers rather than working, so even a modest VPS can hand off far more messages per hour than a new sending IP will be permitted to deliver. What actually caps you is reputation: receiving providers decide how much they accept from your address based on your complaint rate, bounce rate and history, and a brand-new IP is simply unknown to them — which in practice means throttled. That is why warm-up takes weeks, why a purchased list can end a new IP in one campaign, and why a larger plan does not increase how much mail gets delivered. Buy server capacity for your campaign software and its database, and treat volume as something you earn rather than something you purchase.

The binding constraint: IP reputation and list quality, not hardware.
Bandwidth: never a limit — a message is a few kilobytes.
CPU and RAM: matter for campaign software and the database, not the MTA.
New IP: unknown, therefore throttled. Warm-up is measured in weeks.
Authentication: without SPF, DKIM, DMARC and matching rDNS, volume is academic.
Only hard published figure: Postal needs 2 cores, 4 GB RAM, 25 GB disk.

What Actually Limits Your Sending

In order. The first four are the ones that bind; the last three are what hosting pages like to talk about instead.

Your IP reputation The real cap. Receiving providers decide how much they will accept from your address, and they decide it from your complaint rate, bounce rate and history. A brand-new IP is not trusted or distrusted — it is unknown, which in practice means heavily throttled. The cap
Your list quality Complaints and hard bounces damage reputation faster than anything else. A purchased list will destroy a new IP within one campaign, regardless of the server it left from — and it breaches our acceptable use policy. The cap
Authentication SPF, DKIM, DMARC and a reverse DNS record matching your sending hostname. Missing any of these does not slow you down — it gets messages filtered or rejected outright, which looks like a volume problem but is not. The cap
Per-provider acceptance rates Each large receiving provider applies its own limits, and will defer you when you exceed them. Well-behaved sending means backing off when told to, which is exactly what a commercial MTA gives you fine control over. The cap
CPU and RAM Almost never the constraint for a plain MTA. Postfix relaying to the internet is not computationally expensive; it spends its life waiting for remote servers. Campaign software and its database use far more than the mail server does. Rarely
Disk speed Matters for the queue and for the campaign database rather than for raw throughput. Segmenting a large list is a database operation, and that is where slow storage shows up first. Rarely
Network bandwidth Effectively never a limit for email. A message is a few kilobytes; a gigabit port could saturate any realistic sending rate many times over. Bandwidth marketing on email hosting pages is noise. Never

Notice that the four real constraints are all things you control, and the three weak ones are all things a host sells you. That asymmetry is why volume figures on hosting pages should be read sceptically — including any we might have been tempted to publish.

How to Find Your Own Number

Rather than a table we invented, here is the method that produces a figure which is actually true for you.

Authenticate before you send anything

SPF, DKIM and DMARC on your sending domain, and a reverse DNS record matching the hostname your mail server announces. Without these, everything you learn from the next steps is measuring the wrong thing. We set the PTR record on request; the rest are DNS records you publish.

Send to your most engaged people first

Opens and clicks from real subscribers are the positive signal that builds reputation. Starting with your least engaged segment does the opposite, and on a cold IP it does it fast.

Increase gradually and watch deferrals

Raise volume in steps over weeks. A deferral is a receiving provider telling you that you have reached its current limit for your IP — the correct response is to slow down, not to retry harder. Your mail log is the measurement instrument.

Treat complaints as the hard ceiling

Complaint rate is the number that ends sending careers. If it climbs, the problem is the list or the content, and no amount of server or software will fix it. Remove unengaged subscribers rather than mailing them harder.

The one thing guaranteed to give you a very low number is a purchased or scraped list. It will generate complaints immediately, burn the IP, and breach our acceptable use policy — at which point sending gets disabled on the affected server. Opt-in only, genuinely.

Sending Volume Questions

Buy the server for your software. Earn the volume.

From $4.95 a month with Port 25 open, a dedicated IPv4 and reverse DNS set free on request — the three things that let you build a reputation at all.

See All 16 Plans Ask Before You Order