If they're hitting the outbound SMTP servers, there's no way (at least that I know of) to protect the IP/servers via obfuscation with a service like Cloudflare etc. Email deliverability relies heavily on the source IP of the sending SMTP for reputation and is going to be viewable in the headers of an email. Also changing IPs isn't a small task unless you're sitting on a load of good reputation IPs that are... - Source: Hacker News / over 2 years ago

Apollo.io seems popular for cold email. Source: 7 months ago

FAAANGM + ATlassian/Uber and similar product based companies 85 lacs - 1.1 cr Startups like coinbase / apollo.io / rippling 80+. Source: 9 months ago

Their data seems pretty good and their features are awesome, but they had a couple of glitches this week that are annoying me. I know they seem to be the best, but has anyone bested them yet? Curious if there's anything out there that's better than Apollo.io. Source: 11 months ago

Tons of options: apollo.io is popular and affordable. If you're looking for recently funded company contact info, saasydb.com is good. Source: 12 months ago

I agree with most people here in that its invaluable. Especially when paired with some other tools like apollo.io and autobound.ai. Source: 12 months ago