Here is the list of IP addresses you'll need to whitelist for different data centers:
https://flow.zoho.com
If you want to allow-list the complete range:
136.143.160.0/19
135.84.80.0/22
165.173.128.0/18
204.141.32.0/23
204.141.42.0/23
If you want to allow-list specific ranges:
US4
204.141.42.0/23
136.143.190.0/23
136.143.186.0/23
136.143.189.0/24
EU1
31.186.243.0 /24
185.20.209.0 /24
185.230.212.0/23
Proxy Outgoing IPs:
31.186.243.98/32
185.20.209.98/32
185.230.212.98/32
EU2
87.252.213.0/24
89.36.170.0/24
185.230.214.0/23
Proxy Outgoing IPs:
87.252.213.98/32
89.36.170.98/32
185.230.214.98/32
IN1
169.148.148.0/23 (PI-IP)
169.148.146.0/23 (PI-IP)
103.103.196.0/24 (PI-IP)
103.103.197.0/24 (PI-IP)
103.117.158.0/24 (PI-IP)
Proxy Outgoing IPs:
125.17.151.90
169.148.146.23
AU1
101.97.36.0/24
103.138.128.0/23
Proxy Outgoing IPs:
101.97.36.36
193.118.160.0/24 - JP1 Edge IP
199.67.84.0/24 - CA1 Edge IP
199.67.86.0/24 - CA2 Edge IP
199.67.85.0/24 - (PI-IP)
Proxy Outgoing IPs:
SA1
199.67.80.0/23
Proxy Outgoing IPs:
199.67.80.21