What this is for#
You've heard "throttle," "rate limit," and "sending limit" used like they mean the same thing. They don't. Two are something you set; the rest are decided by other people's servers. This guide draws the line clearly, then shows you the one control you actually have in AcelleMail — the per-sending-server Sending limit.
The two words people mix up#
Throttle is your side. You decide to pace how fast AcelleMail hands messages to a sending server — say, no more than 1,000 emails an hour. It's a voluntary cap you set. If you hit it, the rest of your campaign simply waits in the queue and goes out as the window rolls forward. Nothing fails; it just spreads over time.
Rate limit is their side. The receiving mailbox provider (Gmail, Yahoo, a corporate mail server) decides how much mail it will take from you in a given window. You don't set this and you can't see the exact number — it's the provider's call, often tied to your reputation. When you bump into it, the receiving server temporarily defers your mail with a "try again later" style response, and AcelleMail retries on its normal schedule.
The short version:
| Term |
Who sets it |
What happens when you hit it |
| Throttle (you, in AcelleMail) |
You |
Remaining mail queues, then sends in the next window — no failure |
| Rate limit (the receiver) |
Gmail / Yahoo / the recipient's mail server |
Receiver defers with a temporary "try later" response; AcelleMail retries |
Everything else you might have read — vendor daily caps, per-domain throttling scripts — is either your email vendor's own contract limit (you manage that in your vendor's dashboard, not in AcelleMail) or behaviour on the receiving side that no email tool controls. The only knob that lives inside AcelleMail is the throttle, and it's called the Sending limit.
The one control you set: Sending limit#
The Sending limit is set per sending server. Two servers can have two different limits — handy when you run a fast transactional server and a paced marketing one.
Open the sending-server detail#
In AcelleMail's sidebar, click Sending → Sending servers. The list shows every server connected to this account, with its Sending limit, Status, and Created date:
The Sending limit column tells you each server's current cap at a glance — for example 1,000 / hour, or Unlimited if no cap is set. Click the server name to open its detail page.
Set the limit#
On the server's detail page, find the Configuration card and the Sending limit dropdown. It offers a short list of presets:
- Unlimited — no pacing; AcelleMail sends as fast as the server accepts
- 100 emails per 1 minute
- 1,000 emails per 1 hour
- 10,000 emails per 1 day
- Custom — pick your own number and window
Choose Custom and three more fields appear: Per (the count), Every (how many time units), and Unit (Minute / Hour / Day). So "5,000 every 2 hours" is Per 5000, Every 2, Unit Hour. Click Save configuration.
That's the whole feature. AcelleMail enforces the cap for that server — when the rolling-window count reaches your number, the queue holds the rest until the window slides forward. You don't add anything to your campaigns; you set it once on the server.
When to set a limit (and when not to)#
| Situation |
Set a Sending limit? |
| Warming a brand-new IP or domain |
Yes — start low and raise it over days |
| Established server, steady volume |
Optional — leave it Unlimited, or set a cap as a safety brake |
| Big one-off campaign blast |
Yes — pace it so you don't dump everything in one spike |
| Transactional / password-reset server |
No — those need to go out immediately; leave it Unlimited |
| Several servers sharing the load |
Yes — a per-server cap divides the volume across them |
A limit that's too low just makes campaigns crawl for no reason. A limit that's sensible protects a young IP and smooths out spikes. Match the number to what you actually send, not to a number that "feels safe."
Common issues#
| What you see |
What it means |
What to do |
| A campaign sends far slower than expected |
The server's Sending limit is set low |
Open the server → Configuration → raise the Sending limit (or set it to Unlimited) |
| Sends pause, then resume in bursts |
Normal — the rolling window filled up, then reset |
Nothing to fix; raise the limit only if the pace is too slow for you |
| Mail to one provider keeps getting deferred and retried |
That receiver is rate-limiting you (their side, not yours) |
This isn't a Sending limit problem — see the deliverability guides below; check bounces and reputation |
The Sending limit column shows Unlimited and you wanted a cap |
No limit was ever set on that server |
Set one via the Configuration card and Save configuration |
What to do after#
- Decide whether each of your servers should be capped or Unlimited, and set them in Sending → Sending servers.
- If deferrals are coming from the receiving side, work the deliverability angle instead — start with bounce decoding and an incident runbook.
- Spreading volume across more than one server? See the multi-server guides below.
Related articles#
