Is autodiscover-s.outlook.com safe?

This message came up in Outlook on my iMac:

"Outlook was redirected to the server autodiscover-s.outlook.com to get new settings for your account.  Do you want to allow this server to configure your settings?"

Options are either Allow or Deny.

Why is this message coming up and is it safe to allow? What are the pros and cons of allowing, what are the pros and cons of denying?

Thanks!