Proposal: Add an async email validation function using dnspython’s async resolver

I maintain a high-volume lead-gen API that validates thousands of emails per request. To keep latency low, we can’t rely on the library’s check_deliverability=True option because it triggers blocking DNS lookups. Instead, we run the library with deliverability checks disabled and perform our own async DNS queries via dns.asyncresolver.

It would be a real improvement if the library exposed a first-class async deliverability path. Below is a minimal prototype showing what that could look like:

from email_validator import validate_email, EmailNotValidError, ValidatedEmail
import dns.asyncresolver

dns_resolver = dns.asyncresolver.Resolver()

async def _resolve_mail_hosts(domain: str):
    try: return await dns_resolver.resolve(domain, "MX")
    except Exception:
        for record_type in ("A", "AAAA"):
            try: return await dns_resolver.resolve(domain, record_type)
            except Exception: continue
        return None

async def aio_validate_email(email: str) -> ValidatedEmail:
    email_info = validate_email(email, check_deliverability=False)
    if await _resolve_mail_hosts(email_info.domain) is None: raise EmailNotValidError
    return email_info

My plan is to open a PR that adds an async validator fully compatible with your existing Pydantic models, plus tests and documentation. Before I invest the time, are you open to adding async support to the project?

Start by reviewing validate_email, ValidatedEmail, EmailNotValidError, the existing Pydantic models, and the proposed dns.asyncresolver flow. The work is complete when the project has a first-class async deliverability validator compatible with those models, along with the planned tests and documentation.