Mate, I've seen this exact scenario a hundred times. Those directory exports are absolute garbage for outreach. You're not getting decision-makers - you're getting reception desks that bin everything not addressed to "Manager."
Prospeo's decent at swapping info@ for firstname@, but the real issue is your source. If you're scraping directories for local leads, you're wasting time. For local service businesses, you need verified mobile numbers and direct emails from Google Business Profile citations or review sites. Even then, first contact needs to be a phone call or a physical touchpoint (flyer, postcard) before you hammer their inbox.
Your copy length isn't the main problem - it's that you're emailing people who never opted in, from a domain that screams "scraper." Clean the list, enrich properly, and lead with value (e.g., "I noticed your map listing is missing the call tracking number..."). Otherwise you'll keep hitting zero.