Updated · Volt Ghost team
fastmail.com MX records
We read these records from Cloudflare's public DNS-over-HTTPS resolver on 30 October 2026. fastmail.fm, Fastmail's older domain, returned exactly the same records.
| Priority | Mail server (MX host) | Role |
|---|---|---|
| 10 | in1-smtp.messagingengine.com | Primary |
| 20 | in2-smtp.messagingengine.com | Backup |
The host names don't mention Fastmail at all: the servers live under messagingengine.com. When we checked, the primary name returned eight IPv4 addresses and the backup four, the same order of size as Yahoo (eight per host) and well above Gmail (one per host). A domain with these two hosts in its MX is almost always hosted on Fastmail, and our email host lookup labels it that way.
Fastmail's sender authentication records
| Record | Where it lives | Value on 30 Oct 2026 |
|---|---|---|
| SPF | fastmail.com TXT | v=spf1 include:spf.messagingengine.com ~all |
| DMARC | _dmarc.fastmail.com TXT | v=DMARC1; p=none; rua=… (reports to a third-party DMARC reporting service) |
| MTA-STS | _mta-sts.fastmail.com TXT plus policy file | v=STSv1; id=20260728T132000, policy mode: testing, mx: *.messagingengine.com |
| TLS reporting | _smtp._tls.fastmail.com TXT | v=TLSRPTv1, same reporting service |
- SPF: the included record
spf.messagingengine.comlists three IPv4 ranges and ends in-all, so the whole check is strict even though fastmail.com's own record ends in~all. - DMARC p=none: monitor-only, like gmail.com. Fastmail collects reports on who sends as fastmail.com without asking receivers to quarantine or reject. Compare Zoho's p=reject and Proton's p=quarantine.
- MTA-STS with a wildcard: the policy allows any
*.messagingengine.comhost rather than naming the two above, and runs in testing mode, so TLS failures are reported but don't block delivery. The policy id shows it was last changed in July 2026.
Why look up Fastmail's records
The usual reason is setting up or checking a custom domain on Fastmail: once your MX points at the two hosts above, mail is flowing to Fastmail. Senders debugging a bounce from in1-smtp.messagingengine.com now know it came from Fastmail's receiving side. To see how a message you received scored on SPF and DMARC, paste its headers into our email header analyzer.
Fastmail versus a temp inbox
Fastmail is a paid mailbox built for keeping mail for years, often with aliases for each site you sign up to. A temporary inbox such as Volt Ghost suits the opposite case: one sign-up you won't come back to, with no account at all. Temp mail vs email alias compares the two approaches.
Questions
What is the MX record for fastmail.com?
fastmail.com has two MX records: in1-smtp.messagingengine.com at priority 10 and in2-smtp.messagingengine.com at priority 20.
What is messagingengine.com?
It is the domain Fastmail runs its mail servers under. Seeing *.messagingengine.com in a domain's MX records is a strong sign the domain's mail is hosted by Fastmail.
Does a custom domain on Fastmail use the same MX records?
Yes, custom domains on Fastmail point at the same in1-smtp and in2-smtp.messagingengine.com hosts, which is how our email host lookup identifies them.
Is fastmail.com a disposable email domain?
No. Fastmail is a paid, permanent mailbox provider and its domains are not on the public disposable-domain list our checker uses.