Daily Limits, Rate Limits, and Capacity in Sendblue
Last updated: April 12, 2026
Last Updated: April 12, 2026
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If messages stop after a burst of sending or after you add a large number of new contacts, this guide helps you separate daily usage limits from rate/pacing issues.
The difference
| Concept | What it means | What it affects |
|---|---|---|
| Daily usage / new-contact capacity | How many brand-new contacts you can start conversations with in a day. | New conversations |
| Rate limit / pacing | How quickly messages are being sent in a short window. | Send speed and burst behavior |
| Overall line health | How healthy and trusted a line looks based on volume, spacing, and engagement. | Longer-term deliverability |
Best-practice operating guidance
Keep new contacts per line to about 50 or fewer per day.
Keep total daily conversations per line around 150 or fewer as a general best-practice guardrail.
Spread new outreach across the day instead of clustering it into a short window.
Aim for an average gap of about 8 minutes or more between new contacts on the same line over the course of the day.
What healthy pacing looks like
If you send to 50 new contacts in a day, that should be distributed over roughly 6.5 hours or longer.
Follow-ups should be triggered by when that contact engaged or opted in, not because a batch fires at the same clock time for everyone.
What to do if you are hitting limits
Slow down the rate at which new contacts are added.
Distribute traffic across additional lines if your use case requires more volume.
Review your automation timing so sends are not bunching together.
If you consistently outgrow the current pacing/usage model, talk to the team about how your account should scale safely.