This page lists the public IP addresses associated with the Leon platform, grouped by what they are used for. These addresses can change over time, so please refer back to this page (and the linked live sources) rather than storing a static copy of the numbers in your own systems.
Outbound API & webhook traffic
If you use Leon's API integrations, webhooks or similar outbound connections, Leon will contact your systems from one of the following addresses:
This list is grouped by environment (production and dev) and may change over time. Please fetch it directly from the link above rather than hardcoding the addresses, and check it again periodically if you use it to configure a firewall.
Outbound system emails
Some emails from Leon are automated system notifications sent directly by the platform itself — for example messages from do-not-reply@leonsoftware.com. These “classic” system emails are sent through Leon's own mail servers, published under the hostname mailsender.internal.leon.aero.
If your account instead sends emails through your own connected mailbox (e.g. your company's Outlook or Gmail integration), those emails are delivered through your mailbox provider's own infrastructure, not through the addresses below.
The addresses behind mailsender.internal.leon.aero may change over time, so please resolve the hostname yourself rather than copying a static list of numbers:
dig +short mailsender.internal.leon.aero
(On Windows: nslookup mailsender.internal.leon.aero.)
Reaching the Leon application
leon.aero, www.leon.aero, and your own Leon subdomain are served through AWS Global Accelerator, which provides the Leon platform with a set of fixed public entry points.
For production environments, the address behind your own Leon subdomain is stable. You can look it up at any time by resolving your own subdomain directly:
dig <your-subdomain>.leon.aero
(On Windows: nslookup <your-subdomain>.leon.aero.)
We don't publish a single, consolidated list of all Leon IP addresses on this page. Each operator only ever needs the address behind their own subdomain — addresses used by other operators aren't relevant to your setup, and publishing a full list would unnecessarily expose details of our internal infrastructure. If you need to allow network access to Leon, please resolve your own Leon subdomain as shown above rather than relying on a shared list.