Email Throttling and Rate Limits Explained
Each ESP and ISP enforces its own sending rate limits. Learn the per-provider limits and how to configure throttling in AcelleMail to stay within them.
IP Warmup Schedule for New Sending Servers
Why Warm Up?
New IPs have zero reputation. If you send thousands of emails immediately, ISPs will flag you as a potential spammer. Warming up gradually builds trust.
Recommended Schedule
| Week | Day | Daily Volume | Cumulative | Notes |
|---|---|---|---|---|
| 1 | 1-2 | 50 | 100 | Most engaged subscribers only |
| 1 | 3-4 | 100 | 300 | Monitor for bounces |
| 1 | 5-7 | 250 | 1,050 | Check inbox placement |
| 2 | 8-10 | 500 | 2,550 | Review reputation dashboards |
| 2 | 11-14 | 1,000 | 6,550 | |
| 3 | 15-18 | 2,500 | 16,550 | |
| 3 | 19-21 | 5,000 | 31,550 | Google Postmaster check |
| 4 | 22-25 | 10,000 | 71,550 | |
| 4 | 26-28 | 25,000 | 146,550 | |
| 5 | 29-35 | 50,000 | 496,550 | |
| 6+ | 36+ | Full volume | - | Maintain consistency |
AcelleMail Configuration
Set per-server sending limits to enforce the warmup schedule:
Admin → Sending Servers → Edit → Sending Limit
Day 1-2: 50 emails per day
Day 3-4: 100 emails per day
...adjust weekly
Monitoring During Warmup
Key Metrics to Watch
- Bounce rate: Must stay below 2%
- Complaint rate: Must stay below 0.1%
- Inbox placement: Use Google Postmaster Tools
Red Flags (Stop and Investigate)
- Bounce rate exceeds 5%
- Complaint rate exceeds 0.3%
- Emails deferred by major ISPs (Gmail, Yahoo)
- IP listed on any blacklist (check mxtoolbox.com)
Tools for Monitoring
# Check blacklists
curl -s "https://mxtoolbox.com/api/v1/Lookup/blacklist/?argument=YOUR_IP"
# Check Google Postmaster Tools
# → https://postmaster.google.com/
Tips for Success
- Start with your best subscribers — recent openers and clickers
- Send consistently — don't skip days during warmup
- Separate by ISP — warm up Gmail, Yahoo, Outlook independently if possible
- Use authentication — SPF, DKIM, DMARC must be configured before warmup
- Avoid purchased lists — only send to confirmed opt-in subscribers
Related Articles
Understanding Email Bounce Types
Hard bounces and soft bounces behave very differently. Learn the SMTP codes behind each type and how AcelleMail handles them to protect your sender reputation.
Configuring Amazon SES with AcelleMail
Step-by-step guide to connecting Amazon Simple Email Service as your sending server in AcelleMail.
More in Sending & Deliverability
View all →Configuring Amazon SES with AcelleMail
Step-by-step guide to connecting Amazon Simple Email Service as your sending server in AcelleMail.
How to Set Up SPF, DKIM, and DMARC Records
Complete guide to configuring email authentication DNS records for maximum deliverability.
Email Throttling and Rate Limits Explained
Each ESP and ISP enforces its own sending rate limits. Learn the per-provider limits and how to configure throttling in AcelleMail to stay within them.
Configuring Multiple Sending Servers
Use a pool of sending servers to distribute campaign load, achieve IP rotation, and set up automatic failover when one server goes down.
Ready to start sending?
AcelleMail is the self-hosted email marketing platform you control end-to-end.
View Pricing