Catch-all report
Is fastmail.com a catch-all domain?
This report shows the mail configuration for fastmail.com and runs a live catch-all probe. A catch-all (accept-all) domain accepts mail for every address, which makes verifying individual fastmail.com mailboxes less certain.
Test a domain for catch-all
This opens one SMTP conversation with the domain's mail server and asks whether a random mailbox is accepted. Many networks block outbound port 25, so a single check can be inconclusive.
Catch-all domains need smarter verification
On a catch-all domain, the server accepts everything, so SMTP alone cannot tell a real mailbox from a typo. Verifly combines multiple signals and flags catch-all addresses so you can decide how to send.
Verify a whole list with 100 free creditsMail configuration for fastmail.com
fastmail.com accepts mail through 2 MX hosts.
| Priority | Mail server (MX) |
|---|---|
| 10 | in1-smtp.messagingengine.com |
| 20 | in2-smtp.messagingengine.com |
What catch-all means for fastmail.com
When a domain is catch-all, its server returns a 250 OK for any recipient — ceo@fastmail.com, sales@fastmail.com, or pure gibberish alike. That is convenient for the domain owner (typos still arrive) but it removes the signal a verifier relies on: acceptance no longer proves the mailbox exists.
The right way to treat a catch-all fastmail.com address is as a middle tier — riskier than a confirmed mailbox, safer than a hard-invalid or disposable one. Verifly returns a dedicated is_catch_all flag so you can decide how aggressively to send instead of guessing.
FAQ — fastmail.com catch-all & verification
- Is fastmail.com a catch-all domain?
- A domain is catch-all when its mail server accepts mail for any address, including ones that do not exist. Run the live probe above to test fastmail.com right now — it opens one SMTP conversation and asks the server whether a random, non-existent mailbox is accepted.
- What are the MX records for fastmail.com?
- fastmail.com routes mail through: in1-smtp.messagingengine.com, in2-smtp.messagingengine.com.
- Why does catch-all matter when verifying fastmail.com addresses?
- On a catch-all domain an SMTP accept does not prove a specific mailbox exists — the server says yes to everything. So a verifier cannot promote a catch-all address to "valid" on acceptance alone; it should flag it separately, which Verifly does.
- How do I verify fastmail.com emails in bulk?
- Use the Verifly API: GET https://verifly.email/api/v1/verify?email=name@fastmail.com with a Bearer key returns a dedicated catch-all flag alongside syntax, MX, disposable and role signals. 100 free credits, no monthly fee.
Verify fastmail.com emails at scale
The Verifly API returns catch-all, disposable, role and SMTP signals in one call — pay-as-you-go, 100 free credits, no monthly fee.