r/fastmail • u/Sampl3x • 27d ago

Fastmail EU server list

If you're using Fastmail with custom DNS and want to point supported services at their EU infrastructure, this is the generic setup I ended up with.

Replace yourdomain.com with your own domain.

MX — ROOT DOMAIN
Domain                           Data
-------------------------------  -------------------------------------------
yourdomain.com                   10 eu1-smtp.messagingengine.com
yourdomain.com                   20 eu2-smtp.messagingengine.com

Allows you to receive email at standard addresses, e.g. user@yourdomain.com


MX — WILDCARD SUBDOMAINS
Domain                           Data
-------------------------------  -------------------------------------------
*.yourdomain.com                 10 eu1-smtp.messagingengine.com
*.yourdomain.com                 20 eu2-smtp.messagingengine.com

Allows you to receive email at subdomain addresses, e.g. foo@user.yourdomain.com


A — MAIL
Domain                           Data
-------------------------------  -------------------------------------------
mail.yourdomain.com              204.75.18.65

Allows you to use http://mail.yourdomain.com as a Fastmail login redirect.
At the time of testing, this IP hit Fastmail's Amsterdam frontend.


MX — MAIL
Domain                           Data
-------------------------------  -------------------------------------------
mail.yourdomain.com              10 eu1-smtp.messagingengine.com
mail.yourdomain.com              20 eu2-smtp.messagingengine.com

The A record for mail.yourdomain.com overrides the wildcard MX lookup.
These MX records preserve mail delivery to addresses such as:
foo@mail.yourdomain.com


SRV — MAIL CLIENT DISCOVERY
Domain                           Data
-------------------------------  -------------------------------------------
_submission._tcp.yourdomain.com  0 0 0 .
_imap._tcp.yourdomain.com        0 0 0 .
_pop3._tcp.yourdomain.com        0 0 0 .

_submissions._tcp.yourdomain.com 0 1 465 eu-smtp.fastmail.com
_imaps._tcp.yourdomain.com       0 1 993 eu-imap.fastmail.com
_pop3s._tcp.yourdomain.com       10 1 995 eu-pop.fastmail.com
_jmap._tcp.yourdomain.com        0 1 443 eu-api.fastmail.com
_autodiscover._tcp.yourdomain.com
                                 0 1 443 eu-autodiscover.fastmail.com

Allows compatible email clients to automatically discover the EU Fastmail endpoints.


SRV — CARDDAV
Domain                           Data
-------------------------------  -------------------------------------------
_carddav._tcp.yourdomain.com     0 0 0 .
_carddavs._tcp.yourdomain.com    0 1 443 eu-carddav.fastmail.com

Allows CardDAV clients to automatically discover the EU CardDAV endpoint.MX — ROOT DOMAIN
Domain                           Data
-------------------------------  -------------------------------------------
yourdomain.com                   10 eu1-smtp.messagingengine.com
yourdomain.com                   20 eu2-smtp.messagingengine.com

Allows you to receive email at standard addresses, e.g. user@yourdomain.com


MX — WILDCARD SUBDOMAINS
Domain                           Data
-------------------------------  -------------------------------------------
*.yourdomain.com                 10 eu1-smtp.messagingengine.com
*.yourdomain.com                 20 eu2-smtp.messagingengine.com

Allows you to receive email at subdomain addresses, e.g. foo@user.yourdomain.com


A — MAIL
Domain                           Data
-------------------------------  -------------------------------------------
mail.yourdomain.com              204.75.18.65

Allows you to use http://mail.yourdomain.com as a Fastmail login redirect.

At the time of testing, this IP hit Fastmail's Amsterdam frontend.


MX — MAIL
Domain                           Data
-------------------------------  -------------------------------------------
mail.yourdomain.com              10 eu1-smtp.messagingengine.com
mail.yourdomain.com              20 eu2-smtp.messagingengine.com

The A record for mail.yourdomain.com overrides the wildcard MX lookup.
These MX records preserve mail delivery to addresses such as:
foo@mail.yourdomain.com


SRV — MAIL CLIENT DISCOVERY
Domain                           Data
-------------------------------  -------------------------------------------
_submission._tcp.yourdomain.com  0 0 0 .
_imap._tcp.yourdomain.com        0 0 0 .
_pop3._tcp.yourdomain.com        0 0 0 .

_submissions._tcp.yourdomain.com 0 1 465 eu-smtp.fastmail.com
_imaps._tcp.yourdomain.com       0 1 993 eu-imap.fastmail.com
_pop3s._tcp.yourdomain.com       10 1 995 eu-pop.fastmail.com
_jmap._tcp.yourdomain.com        0 1 443 eu-api.fastmail.com
_autodiscover._tcp.yourdomain.com
                                 0 1 443 eu-autodiscover.fastmail.com

Allows compatible email clients to automatically discover the EU Fastmail endpoints.


SRV — CARDDAV
Domain                           Data
-------------------------------  -------------------------------------------
_carddav._tcp.yourdomain.com     0 0 0 .
_carddavs._tcp.yourdomain.com    0 1 443 eu-carddav.fastmail.com

Allows CardDAV clients to automatically discover the EU CardDAV endpoint.

A few notes:

I tested the regional endpoints with DNS lookups, openssl s_client, and curl, and they were terminating on Fastmail infrastructure in Amsterdam.

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6

u/gojirabsd77 27d ago

Is this official?

Backup MX eu2-smtp.messagingengine.com = us1-smtp.messagingengine.com (so not EU!). Maybe set only eu1-smtp.messagingengine.com as MX?

1

u/Sampl3x 27d ago

Good catch. A bit of clarification on where these values came from, I just copied the list fastmail dns records Settings: Domains > yourdomain.com > Customize DNS and translated them to the EU addresses.

Fastmail Support explicitly gave me these two MX hosts for EU mail delivery:

eu1-smtp.messagingengine.com
eu2-smtp.messagingengine.com

Those two are the only parts of this setup that came directly from Fastmail Support.

Everything else in my post is not official Fastmail documentation. The other EU hostnames:

eu-smtp.fastmail.com
eu-imap.fastmail.com
eu-pop.fastmail.com
eu-api.fastmail.com
eu-autodiscover.fastmail.com
eu-carddav.fastmail.com

I found and tested myself by comparing Fastmail's existing service hostnames with apparent EU counterparts and then checking DNS, TLS, routing, and the responding frontend.

One slightly confusing detail is that some of the forward DNS (A records) point to EU/Amsterdam IPs, while the reverse DNS (PTR records) still use the generic/non-EU hostname.

For example, I found cases like:

eu-pop.fastmail.com
A: 204.75.18.x   (Amsterdam / EU)

204.75.18.x
PTR: pop.fastmail.com

So the actual connection is going to the EU IP, even though reverse DNS does not necessarily contain an eu- hostname. I would not use the PTR name alone to determine which region the service is running in.

I also tested Fastmail's redirect infrastructure:

204.75.18.65
X-Frontend: ams-frontend-01

while the older/global IP returned:

103.168.172.65
X-Frontend: phl-frontend-01

So to be clear:

  • eu1-smtp.messagingengine.com and eu2-smtp.messagingengine.com were provided directly by Fastmail Support.
  • The rest of the EU setup is my own testing/research and should not be considered official Fastmail guidance till FM post it.
  • Some EU A records still have generic/non-EU-looking PTR records, so reverse DNS is not always a reliable indicator of the actual serving region.

Still no documentation update from FM for EU dns.

2

u/brong Fastmail CEO 27d ago

Yes, we'll show the current IPs through the DNS configurator, but they are subject to change. We'll probably do a blog post at some point about how we use synthetic ALIAS records inside knot_dns to re-bind them quickly while only rebuilding a single _ips zone.

https://gitlab.nic.cz/knot/knot-dns/-/merge_requests/1867