Rate Limiting
Restrictions imposed by email providers on how fast you can send emails, preventing abuse and maintaining system stability.
What is Rate Limiting?
Rate limiting is a restriction on how many requests (in this case, emails) you can make in a given time period. Email providers implement rate limits to:
1. Prevent abuse and spam 2. Maintain system stability 3. Ensure fair resource distribution 4. Protect receiving servers
Common rate limits:
- Microsoft 365: 30 messages/minute
- Google Workspace: Variable, roughly 500/day/user
- Receiving servers: Often limit incoming from single source
Rate limit errors:
- 452 4.5.3 Too many recipients
- 421 4.7.0 Too many connections
- 450 4.2.1 ... try again later
Handling rate limits: 1. Spread sending over time 2. Use multiple sending domains 3. Monitor for rate limit errors 4. Implement backoff when limited
Rate limits are why you can't send 10,000 cold emails from one mailbox in an hour - even if you wanted to.
Why It Matters
- 1Hard limits enforced by providers
- 2Exceeding causes delays or rejections
- 3Requires spreading sends over time
- 4Multiple domains help work within limits
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Related Terms
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