Why Throttling Matters#
Sending too fast triggers spam filters and can get your account suspended. Every receiving mail server — and every sending service — enforces rate limits. Throttling tells AcelleMail to spread your campaign sends over time.
Common Provider Limits#
| Provider |
Default Limit |
Notes |
| Amazon SES (sandbox) |
1 msg/sec, 200/day |
Request production increase |
| Amazon SES (production) |
14 msgs/sec |
Varies by account age |
| SendGrid Free |
100/day |
Upgrade for more |
| SendGrid Essentials |
100 msgs/sec |
|
| Mailgun Flex |
5,000/month free |
|
| Gmail SMTP |
500/day |
Not for bulk use |
| Your own Postfix |
Unlimited* |
Throttle by recipient ISP |
*Sending unlimited via your own server is technically possible but ISPs will throttle or reject bursts — configure wisely.
Configuring Throttling in AcelleMail#
Navigate to Settings → Sending Servers → [your server] and set:
- Speed (emails/hour) — total throughput cap
- Sending limit — optional daily cap
For campaigns, you can also set per-campaign throttling under the Schedule tab.
Per-ISP Throttling Tips#
Gmail, Yahoo, and Outlook each have informal limits for new IPs:
- Start with 200–500/day per ISP on a new IP.
- Ramp up 20–50% per week during warmup.
- Watch your Defer rate — a high defer count means you are sending too fast.
Use AcelleMail's Sending Server Pool to distribute load across multiple servers when a single server's limit is not enough.
