When inviting new Atlas Users to organizations via the API, the invite email says that the invite was sent by the API public key that performed the API call. This makes the invitation emails read like this:

"You have been invited by tfqzvwrs to join the Example - Atlas organization on MongoDB Atlas."

The ability to customize this (e.g. using an additional field in the request body) would be ideal since the random string being shown as the sender of the invite could make the email look suspect.