That would be your collector egress addresses. Generally the only LM-originated access would be from the website check source addresses (documented in the support site).
ProfessorThat will work for lots of folks, but there are also more complex systems out there handling Internet these days where your IP may be less predictable. For example, I have clients on Cato Networks cloud-based SD-WAN where egress can be anywhere in their POP network depending on the target. For those sorts of transport solutions, you can use rules to pin access to specific IP addresses, but by default you would have a hard time defining an allowlist on remote resources. Even for a more common setup where you have dual ISPs in active/backup mode you can be surprised during an outage event. Best to check with your IT team rather than use code like this or tools like ipchicken.com to figure it out yourself.
