The #1 Misconception in Cold Email
Most people think email reputation works at the mailbox level. It doesn't. Email providers block at the domain level.
This is why 10 domains with 2 mailboxes each will always outperform 1 domain with 20 mailboxes.
How Blocking Actually Works
| What Gets Flagged | What Happens | Recovery Time |
|---|---|---|
| Mailbox | Individual sender throttled | Hours to days |
| Domain | ALL mailboxes on domain blocked | Weeks to months |
| IP | All traffic from IP blocked | Varies by provider |
The Math That Matters
Bad Setup: 1 Domain, 20 Mailboxes
- One mailbox triggers spam filters
- Entire domain gets flagged
- All 20 mailboxes stop reaching inboxes
- 100% of your sending capacity gone
Good Setup: 10 Domains, 2 Mailboxes Each
- One domain triggers spam filters
- That domain's 2 mailboxes affected
- 8 other domains continue sending normally
- Only 10% of your sending capacity affected
Why 1-2 Mailboxes Per Domain?
Adding more mailboxes to a domain doesn't increase your safe sending capacity - it just creates more potential triggers for the same domain.
| Mailboxes/Domain | Safe Daily Volume | Risk Level |
|---|---|---|
| 1-2 | 20-50 emails | Low |
| 3-5 | Same 20-50 emails | Medium |
| 10+ | Same 20-50 emails | High |
Action Items
- Audit your current setup - How many domains do you have? How many mailboxes per domain?
- Calculate your risk exposure - If one domain dies, what percentage of capacity do you lose?
- Spread your risk - Aim for 10+ domains with 1-2 mailboxes each
- Monitor domain reputation - Use our Domain Reputation Checker regularly
Key Takeaway
Think of domains like baskets and mailboxes like eggs. You want many baskets with few eggs each - not one basket holding all your eggs.