All Chargify outbound requests (i.e. Webhooks, gateway requests, etc) are currently sent through the following addresses:
126.96.36.199 188.8.131.52 184.108.40.206 220.127.116.11 18.104.22.168 22.214.171.124
You may need these for your firewall or for your payment gateway configuration.
Note: this list is kept up-to-date - this post is edited in place when we make an addition. You do not need to scan all of the comments to find the latest list.