Error user in sharepoint 2013

Hello guys!

I want to resolve the user problem on SharePoint where some users don't have a user profile.

I noticed the problem when some users don't receive emails from the SharePoint application. For example, I have a room reservation system that sends confirmation emails, but some users don't receive them. I noticed that the users who don't receive the email, in the "created by" field on the list, have generic usernames that don't exist (and can't be opened).