# MailSift, free, POST /verify/bulk, Verify a CSV in bulk: Email verification API

> MailSift is a fast, accurate email verification API and bulk CSV validator. It detects invalid, disposable, role-based, and risky email addresses using syntax, MX, SPF, DMARC, SMTP, and catch-all checks, returning a status and a 0–100 deliverability score.

MailSift's email verification API on its Free plan. It costs $0.00 per 1,000 emails. It returns 3 of the 6 key fields we check: Address, Deliverability, Confidence.
We rank 2,467 plans by price. [treg's top-up from $10](https://datacircle.dev/validate-email-apis/treg/top-up-from-10/llms.txt) costs the least per 1,000 emails: $0.00 on average. treg asks one provider after another until one answers. You pay $26.95 per 1,000 emails when no provider answers.
[Enrich.so](https://datacircle.dev/validate-email-apis/enrich-so/149-monthly/llms.txt), [GetProspect](https://datacircle.dev/validate-email-apis/getprospect/369-pack/llms.txt) and [treg](https://datacircle.dev/validate-email-apis/treg/top-up-from-10/llms.txt) are the best email verification API providers in our benchmark.

- This page: https://datacircle.dev/validate-email-apis/mailsift/free-post-verify-bulk-verify-a-csv-in-bulk
- [Best email verification API in 2026](https://datacircle.dev/best-email-verification-api.txt)
- Get it: https://mailsift.dev/pricing
- Request: `POST https://mailsift.dev/api/v1/verify/bulk`, Verify a CSV in bulk
- API key: with the plan, on https://mailsift.dev/pricing
- Its API docs: https://mailsift.dev/api#bulk-workflow
- Sold by: MailSift (https://mailsift.dev)
- Checked: 2026-10-20

## In the answer

- Completeness: 50%
- Address: ✓
- Deliverability: ✓
- Confidence: ✓

## Price

- $ per 1,000 emails: $0.00
- Per: result
- Billing: free

## Aggregators

- Aggregators: none

## Charges

- Also pays for: from the same budget: Verify one email · Verify one email with Deep Verification · Verify up to 100 emails at once · Verify up to 100 emails at once with Deep Verification · Verify a CSV in bulk with Deep Verification

## Not found

- $ per 1,000: $0.00

## Catch-all

- $ per 1,000: $0.00

## In their words

- Their pitch: MailSift is a fast, accurate email verification API and bulk CSV validator. It detects invalid, disposable, role-based, and risky email addresses using syntax, MX, SPF, DMARC, SMTP, and catch-all checks, returning a status and a 0–100 deliverability score.

## Data

- Freshness: stored (MX, SPF, DMARC: live)
- Keep data: no limit
- Use data: You may not use MailSift to: send unsolicited email, harass individuals, build databases of contact information for sale, circumvent rate limits or terms, or for any unlawful purpose. [...] You are responsible for having a lawful basis to process the email addresses you submit, including, where applicable, consent under the GDPR. [...] We grant you a non-transferable, revocable license to use the service for its intended purpose.

## Plan

- Pay: $0
- You get: 500 credits
- Enough for: 500 results, once
- Expires: never

## Rate limit

- Per second: 1

## Speed

- Answer: by polling or webhook

## The call

- You send: file. Optional: mode
- Method: POST
- Path: /verify/bulk

## About the plan

- Plan: Free
- Who can get it: anyone 16 or older

## The 31 fields the plan's answer can hold

job ID, filename, total rows, processed rows, valid count, invalid count, risky count, unknown count, job status, mode, credits reserved, error message, started at, completed at, created at, email, status, sub-status, score, disposable, MX, role address, free provider, relay, blocklisted, SPF, DMARC, domain age, MX provider, normalized email, did you mean

## MailSift's plans (5)

- [MailSift, free, POST /verify/bulk, Verify a CSV in bulk](https://datacircle.dev/validate-email-apis/mailsift/free-post-verify-bulk-verify-a-csv-in-bulk/llms.txt): $0.00 per 1,000, 50% complete, stored (MX, SPF, DMARC: live)
- [MailSift, $10 pack, Starter, POST /verify/bulk, Verify a CSV in bulk](https://datacircle.dev/validate-email-apis/mailsift/10-pack-starter-post-verify-bulk-verify-a-csv-in-bulk/llms.txt): $0.40 per 1,000, 50% complete, stored (MX, SPF, DMARC: live)
- [MailSift, $35 pack, Growth, POST /verify/bulk, Verify a CSV in bulk](https://datacircle.dev/validate-email-apis/mailsift/35-pack-growth-post-verify-bulk-verify-a-csv-in-bulk/llms.txt): $0.35 per 1,000, 50% complete, stored (MX, SPF, DMARC: live)
- [MailSift, $99 pack, Pro, POST /verify/bulk, Verify a CSV in bulk](https://datacircle.dev/validate-email-apis/mailsift/99-pack-pro-post-verify-bulk-verify-a-csv-in-bulk/llms.txt): $0.283 per 1,000, 50% complete, stored (MX, SPF, DMARC: live)
- [MailSift, $249 pack, Enterprise, POST /verify/bulk, Verify a CSV in bulk](https://datacircle.dev/validate-email-apis/mailsift/249-pack-enterprise-post-verify-bulk-verify-a-csv-in-bulk/llms.txt): $0.249 per 1,000, 50% complete, stored (MX, SPF, DMARC: live)

## MailSift's calls (6)

- `POST /verify/bulk`, Verify a CSV in bulk: [MailSift, free, POST /verify/bulk, Verify a CSV in bulk](https://datacircle.dev/validate-email-apis/mailsift/free-post-verify-bulk-verify-a-csv-in-bulk/llms.txt)
- `POST /verify/bulk`, Verify a CSV in bulk with Deep Verification: [MailSift, free, POST /verify/bulk, Verify a CSV in bulk with Deep Verification](https://datacircle.dev/validate-email-apis/mailsift/free-free-post-verify-bulk-verify-a-csv-in-bulk-with-deep-verification/llms.txt)
- `GET /verify`, Verify one email: [MailSift, free, GET /verify, Verify one email](https://datacircle.dev/validate-email-apis/mailsift/free-get-verify-verify-one-email/llms.txt)
- `GET /verify`, Verify one email with Deep Verification: [MailSift, free, GET /verify, Verify one email with Deep Verification](https://datacircle.dev/validate-email-apis/mailsift/free-free-get-verify-verify-one-email-with-deep-verification/llms.txt)
- `POST /verify/batch`, Verify up to 100 emails at once: [MailSift, free, POST /verify/batch, Verify up to 100 emails at once](https://datacircle.dev/validate-email-apis/mailsift/free-post-verify-batch-verify-up-to-100-emails-at-once/llms.txt)
- `POST /verify/batch`, Verify up to 100 emails at once with Deep Verification: [MailSift, free, POST /verify/batch, Verify up to 100 emails at once with Deep Verification](https://datacircle.dev/validate-email-apis/mailsift/free-free-post-verify-batch-verify-up-to-100-emails-at-once-with-deep-verification/llms.txt)

## MailSift's APIs (1)

- [MailSift: email verification API pricing, 5 plans, POST /verify/bulk, Verify a CSV in bulk](https://datacircle.dev/validate-email-apis/mailsift/free-post-verify-bulk-verify-a-csv-in-bulk/llms.txt)

## MailSift: email verification API alternatives

- [StopReg, $50 monthly](https://datacircle.dev/validate-email-apis/stopreg/50-monthly/llms.txt): $0.25 per 1,000, 50% complete, stored
- [UserCheck, $50 monthly, Pro 200k, POST /v1/gates/{gate_id}/decisions, Decision endpoint](https://datacircle.dev/validate-email-apis/usercheck/50-monthly-pro-200k-post-v1-gates-gate-id-decisions-decision-endpoint/llms.txt): $0.25 per 1,000, 50% complete, stored
- [Elastic Email, $379 monthly, Email API Starter (1,500,000 emails/month), POST /verifications/files](https://datacircle.dev/validate-email-apis/elastic-email/379-monthly-email-api-starter-1500000-emails-month-post-verifications-files/llms.txt): $0.253 per 1,000, 50% complete, stored
- [ReefAPI, $1,200 yearly](https://datacircle.dev/validate-email-apis/reefapi/1200-yearly/llms.txt): $0.333 per 1,000, 67% complete, stored

## Sources

From each provider's own pricing page and docs, and from what providers tell us. We read this row from these pages on 2026-10-20.

- https://mailsift.dev
- https://mailsift.dev/api
- https://mailsift.dev/docs/api-reference.md
- https://mailsift.dev/docs/overview.md
- https://mailsift.dev/llms.txt
- https://mailsift.dev/openapi.json
- https://mailsift.dev/pricing
- https://mailsift.dev/terms