A company whose domain no longer resolves is not a slow prospect. It is a dead one, and every message to it is a guaranteed bounce charged to your reputation.
The domain checks Sellvance runs on your own sending domains are now available as an enrichment for lead company domains. It records whether the domain resolves, whether it serves a website, and what its mail configuration looks like.
Put it early in a segment's chain with a filter after it, and dead companies never reach the expensive enrichments — let alone a campaign.