# Allowlist our IP addresses

If you use a firewall or an allowlist, you may need to allow traffic from our IP addresses to support traffic from Customer.io based on the features you use.

If you have a custom SMTP server, use our webhooks, or have an outgoing data warehouse integration, you’ll need to allow the appropriate addresses below.

Make sure you allow the appropriate addresses for your region!

Email (Custom SMTP) and Webhook IP Addresses

US Region

EU Region

35.188.196.183

34.76.143.229

104.198.177.219

34.78.91.47

104.154.232.87

34.77.94.252

130.211.229.195

35.187.188.242

104.198.221.24

34.78.122.90

104.197.27.15

35.195.137.235

35.194.9.154

130.211.108.156

104.154.144.51

104.199.50.18

104.197.210.12

34.78.44.80

35.225.6.73

35.205.31.154

136.111.237.157

34.10.127.179

Reverse ETL IP Addresses (data-in)

34.29.50.4

34.22.168.136

35.222.130.209

34.78.194.61

34.122.196.49

104.155.37.221

Data Warehouse IP Addresses (data-out)

34.71.192.245

34.118.255.179

35.188.196.183

34.76.143.229

104.198.177.219

34.78.91.47

35.184.88.76

35.187.55.80

34.72.101.57

104.199.99.65

34.123.199.33

34.76.81.2

35.222.137.61

34.77.146.181

34.68.113.63

34.140.234.108

35.240.84.170

35.195.54.15

34.38.105.52

104.155.66.230

34.76.119.61

34.140.67.73

34.78.74.81