What I want is not add the import user to follow messages.

Edited: Thanks Paresh !!

Must be one of installed modules. I do not have enough karma to mark your response

Hi:

This does not seem to be the default behavior. Tried it in the demo instance and no followers are created by default on the imported records.

Check whether a customization/configuration change has been done.

you can disable notifications by stopping the Automated Mail Actions (setting> technical> Automated Actions)
or follow this video
https://www.youtube.com/watch?v=0yzwW9spQZc