Off-Market Deal Sourcing Tech Stack

For those who have gone the DIY route of off-market email outreach when searching for a business to buy, what programs/software do you recommend for sourcing leads, obtaining contact information, verifying email addresses, and running email campaigns? I'd also appreciate any general advice the community may have on off-market deal sourcing, as I'm preparing to launch a self-funded search for an Atlanta-based business next year. Thanks in advance, and I'd love to connect with anyone in the Atlanta ETA space!