How Many Domains and Inboxes Do You Need for Cold Email?
Mailbox providers watch how many emails each inbox and domain sends. If you send too many from one inbox, your emails start landing in spam. The way around this is to spread your sending across several inboxes on several domains.
Safe sending limits
These are the limits we work to, in line with Instantly's current recommendations:
| Limit | Recommendation |
|---|---|
| Cold emails per inbox, per day | 30 at most (start lower, see Ramp Up) |
| Inboxes per domain | 2 to 3 |
| Warmup before the first campaign | At least 14 days, 30 days is safer |
Fewer emails per inbox and fewer inboxes per domain is always safer.
Calculate what you need
- Inboxes needed = emails you want to send per day / 30
- Domains needed = inboxes needed / 3
Round both numbers up.
For example, to send 600 emails per day you need 20 inboxes (600 / 30) spread across 7 domains (20 / 3).
The setup used in this guide
In this guide I use 2 domains with 3 inboxes on each domain, which is 6 inboxes in total. That lets you send:
- 180 emails per day (6 x 30)
- About 3,800 emails per month, sending on weekdays only
This is a good place to start. It fits within Instantly's entry-level plan, and you can add more domains and inboxes once you are getting good results.
Follow-up emails count towards your daily limit too. If your sequence has 3 emails, a new campaign of 180 people per day will soon be sending more than 180 emails per day. Plan your volume around all emails sent, not just new leads.