Basic IP Allocation
How many sending IP addresses to use, based on daily volume, for a single homogeneous mail stream.
One big question when setting up a new email server is: "how many IP addresses should I be using?"
Scope of this advice
This document assumes you send a single kind of email, with no need to split different kinds of email onto different IP addresses to maintain different reputations. If your needs are more advanced, see Advanced IP Segmentation and Allocation.
It also assumes you are maximizing deliverability of email that is wanted and expected. Deliverability of email that is not wanted and expected may actually suffer from following these recommendations, depending on the details.
Number of IP addresses
| Messages per day | Number of IPs |
|---|---|
| less than 40,000 | One |
| between 40,000 and 200,000 | Two |
| more than 200,000 | Size for 100,000–1,000,000 messages per IP address per day |
Don't use too many IP addresses
Spreading mail over too many IP addresses looks like a spamming technique called "snowshoeing." Snowshoeing spreads a volume of mail over many different IP addresses so that each IP flies "under the radar" with only a small volume. Mailbox providers are aware of this technique and penalize senders when they see mail coming from too many IP addresses relative to the volume.
If you have been snowshoeing and are sending email with a very high complaint ratio or low engagement ratio, read Two Worlds of Email Deliverability before consolidating onto a smaller number of IPs.
Have enough volume on each IP
A single IP address should not send less than 40,000 messages in a week.
You need to send enough email from an IP address for mailbox providers to gather statistically significant engagement and complaint data about your mail.
This is the general per-IP statistical-legibility floor; a dedicated transactional IP can be justified at a lower volume, and individual ESPs set their own minimums. See the canonical dedicated-IP volume floors table for the reconciliation.