Add Presend as a free email-verification tool option (alongside Hunter) #8034

Disclosure: I'm the developer of Presend (https://presend.pages.dev), flagging that upfront -- this is a self-interested suggestion.

Noticed the tools/hunter/ folder includes email_verifier.ts among several Hunter-backed tools (discover, email_finder, domain_search, etc.) -- all requiring a paid Hunter API key beyond a small free tier.

Presend's /api/email-verify does a comparable single-address check for free, no signup, no key: syntax + MX record + disposable-domain + role-account detection in one call. Following the existing tools//.ts pattern, a tools/presend/email_verify.ts alongside the Hunter tools would give workflow builders a no-key fallback option for basic verification, without needing to provision a Hunter key just to check an address before sending.

To be upfront about scope: this doesn't cover Hunter's finder/discovery/company-lookup functionality (email_finder, companies_find, domain_search) -- just the verification check specifically, comparable to email_verifier.ts.

Happy to open a PR matching your existing tool file conventions if this is a direction you'd want -- didn't want to show up with an unsolicited PR on a project this size without checking first.

Docs: https://presend.pages.dev/api#GET-api-email-verify