In context of IP warming, I wonder how (within Marketing Cloud interface) to identify which IP address emails are being sent from.
If you purchased a dedicated IP, you can see it in the Deliver profile:
When you create a delivery profile, you specify the IP address to use. If you do not use a private domain, you select the account default.
If you haven’t purchased your own IP, you’re on a shared one, and there is currently no way to check the IP address from the interface:
By design, it is not currently possible to locate the default IP address used for email sends in your Marketing Cloud account.
For assistance obtaining your account's default IP email sending address, please create a Case with Marketing Cloud Support via Salesforce Help.