If you are getting these errors or users are reporting this error when trying to get access to a site, this might be your problem. Each site collection can set its own email address for access requests, if you allow them. Here is how to fix it.
Go to the top level site of any site collection. Click on Site permissions on the settings page.
- On the page that comes up, click on Access Request Settings.
Change the default value to whatever email you want to receive the requests. Someone@example.com is the default. This is why you are getting the errors.