Domain Intelligence
Last Updated:
Fastmail Email Verification
Safe to Send
Fastmail.com is operated by Fastmail Pty Ltd. The domain runs 2 mail exchanges and SMTP is responsive, with 2 of 3 authentication standards in place.
Safe to Send
RISK
1
/100
Low
Verifying a list of Fastmail addresses?
Bulk verify Fastmail addresses with deep SMTP handshakes. Catch typos, role accounts, and dead mailboxes that hurt your sender reputation. From $9.95 per 10,000 emails.
Verify Mailbox
Verify @fastmail.com emails
Live SMTP handshake against fastmail.com mail servers. No email is sent. 10 free per day, no signup.
Trusted by 400,000+ senders
4.9/5
From 8,500+ verified reviews
Reached out to support during our API integration last month. Response in under 15 minutes, the rep was so sharp and helpful that by the end of the thread it honestly felt like I was flirting with him. Amazing support team. A+++. Nathan Orozco · Lead Engineer · via X
SOC 2 Type II
GDPR
CCPA
99.7% Accuracy
Disposable
No
Persistent addresses, not throwaway
SMTP Live
Yes
Mail server responds to SMTP handshake
MX Records
2
Mail exchangers
Mail Exchange (MX) Records for fastmail.com Mail Exchange records. They tell other mail servers which hosts are responsible for receiving email at this domain, in priority order. Lower priority numbers are tried first.
#10
in1-smtp.messagingengine.com 103.168.172.218
Reachable
#20
in2-smtp.messagingengine.com 202.12.124.218
Reachable
SMTP Handshake
Simple Mail Transfer Protocol. We open a live SMTP connection to the primary MX and read the greeting banner. A response confirms the mail server is alive and accepting connections.
Responsive
BANNER220 phl-mx-06.messagingengine.com ESMTP mx. No UCE permitted.
Primary mail server accepted SMTP connection and returned a banner during the live audit.
fastmail.com Email Authentication SPF · DKIM · DMARC
SPF
Sender Policy Framework. A DNS record listing which servers are allowed to send mail for this domain. Receivers reject or flag mail from unauthorized servers.
Pass
TXTv=spf1 include:spf.messagingengine.com ~all
Authorized senders are defined and pass SPF policy.
DKIM
DomainKeys Identified Mail. The sending server cryptographically signs outbound mail with a private key, and receivers verify the signature using a public key in DNS.
Missing
No DKIM signature detected on common selectors for fastmail.com.
No DKIM signature was detected. Receivers cannot verify the integrity of outbound mail.
DMARC
Domain-based Message Authentication, Reporting & Conformance. Tells receivers what to do when SPF or DKIM checks fail: none, quarantine, or reject.
None
TXTv=DMARC1; p=none; rua=mailto:e3936a44@inbox.ondmarc.com
Monitoring only. Receivers take no action when SPF or DKIM fails.
fastmail.com Domain Registration WHOIS · Nameservers · Registrar
RegistrarGANDI SAS
IANA ID81
RegisteredDecember 8, 1994
Last UpdatedAugust 1, 2025
ExpiresDecember 8, 2034
Age31 years
TLD.com
Authoritative Nameservers (2)
- FMNS1.MESSAGINGENGINE.COM
- FMNS2.MESSAGINGENGINE.COM
Registrant
Hidden by registrar privacy service
Technical Contact
Hidden by registrar privacy service
About this Domain
About fastmail.com
Fastmail is a premium email service operated by Fastmail Pty Ltd, headquartered in Melbourne, Australia. Founded in 1999, Fastmail focuses on providing fast, reliable, and privacy-respecting email without advertising. The service offers advanced features including custom domain hosting, calendar and contacts, and powerful search capabilities for both personal and business users.
fastmail.com implements comprehensive SPF, DKIM, and DMARC authentication for all outbound messages. Fastmail is known for its strong stance on email standards compliance and actively participates in developing email security protocols. The service supports JMAP (JSON Meta Application Protocol) alongside IMAP and provides robust spam filtering powered by its own filtering technology.
The fastmail.com mail servers enforce strict recipient verification and immediately reject messages to nonexistent addresses. The domain does not operate as a catch-all. Fastmail maintains high-quality mail infrastructure with good deliverability practices and standard rate limiting for inbound connections.
For reliable delivery to fastmail.com users, ensure your sending domain has properly configured SPF, DKIM, and DMARC records. Fastmail's spam filtering is sophisticated and rewards proper authentication. Maintain clean lists, honor unsubscribe requests, and follow standard email best practices. Fastmail users tend to be technically savvy, so email quality and standards compliance matter.
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Common Questions About fastmail.com
Is fastmail.com a disposable or temporary email provider?
No. fastmail.com is not a disposable email provider. It is classified as Free Email Provider operated by Fastmail Pty Ltd and addresses on fastmail.com are persistent rather than throwaway. Mail sent to a valid fastmail.com mailbox reaches a real recipient.
How do I verify if a fastmail.com email address is valid?
The fastest way to verify a fastmail.com email address is to use our email checker. Enter any @fastmail.com mailbox at the top of this page and our system performs a real-time SMTP handshake against fastmail.com's mail servers, confirming whether the mailbox exists, is reachable, and is safe to send to. No email is ever delivered during the check.
Can I check if a fastmail.com email exists without sending a message?
Yes. Our real-time email verification API connects directly to fastmail.com's mail server, opens an SMTP session, and queries the mailbox using the RCPT TO command without ever transmitting an actual email. The server's response confirms whether the fastmail.com mailbox is valid, full, or non-existent. The recipient never receives anything and never sees the check.
What are the MX records for fastmail.com?
fastmail.com currently publishes 2 mail exchange (MX) records. The primary MX is in1-smtp.messagingengine.com, which is the first server contacted when other mail systems try to deliver email to a fastmail.com address. The full list with priorities and IP addresses is in the MX Records panel above. MX records tell sending servers where to route email for fastmail.com.
Does fastmail.com use SPF, DKIM, and DMARC email authentication?
fastmail.com has 2 of the 3 standard email authentication records in place: SPF, and DMARC (policy: none). Adding the missing layer(s) would tighten anti-spoofing protection and improve deliverability for legitimate fastmail.com mail.
Why do emails to fastmail.com bounce or get blocked?
Bounces from fastmail.com usually fall into three buckets: the mailbox doesn't exist (5xx user unknown), the inbox is full, or your sending domain isn't authenticated to fastmail.com's satisfaction. The fastest fix is to run each address through a free email verifier before you send, and to make sure your own SPF, DKIM, and DMARC are configured correctly so fastmail.com's receivers trust you.
How can I verify a large list of fastmail.com email addresses?
Our bulk email verifier accepts CSV or TXT uploads with thousands or millions of fastmail.com addresses (or any mix of domains). Every address goes through 30+ checks including SMTP existence, fastmail.com catch-all detection, role-account detection, and disposable-domain matching. Results typically come back within minutes and previously-failed addresses on your blacklist are reprocessed for free. For continuous high-volume needs, see our unlimited email verification API.
Is it safe to accept signups from fastmail.com email addresses?
Yes, with normal hygiene. fastmail.com is a legitimate email service and signups from @fastmail.com behave like any other real user. Pipe each address through a real-time email verifier API at the moment of signup to catch typos and dead mailboxes, but there is no need to block fastmail.com by default.
What email format does fastmail.com use for usernames?
Most fastmail.com mailboxes follow common patterns like first.last@fastmail.com, firstinitiallast@fastmail.com, or first@fastmail.com, but the actual local-part rules depend on Fastmail Pty Ltd. The only reliable way to confirm whether a specific @fastmail.com address exists is to run it through a free email verification tool. Guessing patterns will produce a high bounce rate and damage your sender reputation.
How is the fastmail.com risk score calculated?
The 0-to-100 risk score for fastmail.com combines disposable-domain classification, mail-server reachability, MX record presence and depth, SPF / DKIM / DMARC enforcement, DMARC policy strength, SMTP banner response, and domain age. Lower scores mean safer to send to. Disposable domains are pinned at the high end of the scale. The fastmail.com score is recomputed on every audit so it always reflects the live state of the domain.
Is fastmail.com a valid email domain?
Yes, fastmail.com is a valid email domain operated by Fastmail Pty Ltd, an Australian company. Fastmail is a premium email service known for speed, reliability, and strong privacy practices.
Is fastmail.com a disposable or temporary email provider?
No, fastmail.com is not a disposable email provider. It is a premium permanent email service that has been operating since 1999. Fastmail focuses on performance and standards compliance.
What mail server does fastmail.com use?
Fastmail operates its own mail servers. MX records point to in1-smtp.messagingengine.com and in2-smtp.messagingengine.com, hosted by Fastmail's Messaging Engine infrastructure.
Can I send marketing emails to fastmail.com addresses?
Yes, with proper consent. Fastmail users tend to be technically savvy and use robust filtering. Ensure proper authentication and maintain clean sending practices for deliverability.
How do I verify an email address at fastmail.com?
Fastmail addresses can be verified via SMTP checks with reliable accept/reject responses. Fastmail supports plus-addressing and subdomain addressing for creating aliases.