It Depends - fastmail.com consumer vs custom domains on Fastmail

Is Fastmail a Catch-All Domain?

fastmail.com consumer

Not catch-all - individually verifiable

Custom domains on Fastmail

Frequently catch-all - Fastmail explicitly supports it

Fastmail's own domains (fastmail.com, fastmail.fm, etc.) are not catch-all. But Fastmail is popular among technical users who host custom domains, and Fastmail explicitly supports catch-all mailboxes on paid plans. BounceZero detects catch-all at the domain level and applies ML scoring where SMTP gives an accept-all response.

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Listed

AWS

Activate

Google

for Startups

NVIDIA

Inception

MongoDB

Atlas

Datadog

Startup Program

UK Ltd Co.

No. 17153835

Fastmail Consumer Domains - All Verifiable

fastmail.com

fastmail.fm

fastmail.net

fastmail.org

fastmail.to

fastmail.cn

Fastmail Custom Domain Catch-All - A Common Setup

Fastmail's Standard and Professional plans allow custom domain hosting with catch-all mailbox configuration. This is explicitly documented and widely used - technical users and freelancers commonly configure catch-all on their personal domains hosted on Fastmail to receive all email regardless of which alias is used. When you encounter a custom domain MX-pointing to Fastmail's servers, there is a meaningful chance it is catch-all. BounceZero detects this with a test probe before classifying the address.

Frequently Asked Questions

Is Fastmail catch-all?

Consumer domains (fastmail.com, fastmail.fm, etc.) are not catch-all. But custom domains on Fastmail paid plans frequently enable catch-all. BounceZero detects both cases.

Does Fastmail support catch-all mailboxes?

Yes - Fastmail's Standard and Professional plans explicitly support catch-all mailbox configuration on custom domains. Many users enable it.

Are Fastmail addresses high-quality leads?

Typically yes. Fastmail attracts technical, privacy-conscious users. Valid Fastmail addresses tend to be from engaged, intentional users - lower risk than legacy freemail addresses.

How much does it cost?

$3 per 1,000 verifications. 100 free credits on signup - no credit card required.

Verify Fastmail Addresses - Consumer and Custom Domains.

Catch-all detection included on every domain. 100 free credits to start.

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Is [provider] a catch-all domain?

Per-provider answers - SMTP behaviour, detection methods, and how BounceZero handles each

Is Gmail catch-all?

No - returns 550 for unknown addresses

Is Outlook catch-all?

No - but blocks verifier IPs (Microsoft PTR policy)

Is Yahoo catch-all?

No - but throttles SMTP probes heavily

Is Hotmail catch-all?

No - runs on same Microsoft infra as Outlook

Is iCloud catch-all?

No - icloud.com/me.com/mac.com all individually verifiable

Is ProtonMail catch-all?

Not by design - but SMTP gateway returns 250 for all

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