As per our Advanced Search article, you can enter Contacts Email Addresses that you wish to exclude, however in ’Settings’ you can do a bulk upload of Domains to the Domain Suppression tab.

First you'll need to 'Select' Settings in the top right of the blue banner.

Scroll down to Prospects/Accounts and 'Select' Suppression.

As shown below 'Select' +Add Domain and by selecting Excel you can do a bulk upload of Domains or the Single Domain option.

Reach out to your CSM if you have any questions via email or through the in app chat service.