Strategies for Determining Total Addressable Market for MSPs

Hey guys I'm trying to find out my whole total addressable market in the USA. We target managed IT service providers. It does not have a specific industry so what I'm doing is either downloading company results from Apollo or scraping Google results with serper.dev Then validating that they are indeed an MSP (the abbreviation) using clay gent with 04 mini. The issues that I have: 1 I'm not sure if this process is comprehensive enough 2 I need to produce 1,000 emails a day but at each stage of the process the numbers go something like this 10k companies>5000 are MSP>3000 I find people for > 1500 people enriched> 1000 are valid One of the solutions is maybe emailing their role based email whenever we do not find emails but would like to hear more comprehensive TAM building solutions THANK YOU