This page provides details on advanced domain setup options in Fastmail, and is meant for more technical users. DNS is a complicated system that can break your website and/or mail delivery, so we strongly suggest that you do not make any changes to your DNS unless you have an understanding of DNS, or are following explicit instructions.
Looking for basic information or instructions for setting up your domain in your Fastmail account? Please see our Custom domains with Fastmail help page.
Looking for general background information on how DNS works? Please see our General DNS info help page.
Full list of DNS records
This is the full list of DNS records we can publish for you. You can choose to disable any of these.
All entries have a 1 hour TTL.
Websites
Allows you to host websites at http://{mydomain.com} from your Fastmail file storage.
| Type | Host | Value |
| CNAME | www.{mydomain.com} |
web.fastmail.com |
Standard Mail
Allows you to receive email at standard addresses, e.g. user@{mydomain.com}.
| Type | Host | Value | Priority |
| MX | @ |
in1-smtp.messagingengine.com |
10 |
| MX | @ |
in2-smtp.messagingengine.com |
20 |
Subdomain Websites
Allows you to host websites at subdomains, including http://www.{mydomain.com}, from your Fastmail file storage.
| Type | Host | Value |
| CNAME | *.{mydomain.com} |
web.fastmail.com |
Subdomain Mail
Allows you to receive email at subdomain addresses, e.g. foo@user.{mydomain.com}.
| Type | Host | Value | Priority |
| MX | *.{mydomain.com} |
in1-smtp.messagingengine.com |
10 |
| MX | *.{mydomain.com} |
in2-smtp.messagingengine.com |
20 |
Webmail Login Portal
Allows you to log in to your account at http://mail.{mydomain.com}.
| Type | Host | Value |
| CNAME | mail.{mydomain.com} |
mail.fastmail.com |
Allow mail at subdomains
An A record hides the wildcard subdomain MX record. Setting up the below MX records overrides this to allow receiving email addressed to foo@mail.{mydomain.com}.
| Type | Host | Value | Priority |
| MX | mail.{mydomain.com} |
in1-smtp.messagingengine.com |
10 |
| MX | mail.{mydomain.com} |
in2-smtp.messagingengine.com |
20 |
DKIM
Allows us to sign the mail you send so receivers can verify it's from you. This is important to ensure your message is not classified as spam. Note you'll need to add all three CNAME records.
| Type | Host | Value |
| CNAME | fm1._domainkey.{mydomain.com} |
fm1.{mydomain.com}.dkim.fmhosted.com |
| CNAME | fm2._domainkey.{mydomain.com} |
fm2.{mydomain.com}.dkim.fmhosted.com |
| CNAME | fm3._domainkey.{mydomain.com} |
fm3.{mydomain.com}.dkim.fmhosted.com |
Deprecated (only in use by domains that have been hosted at Fastmail before 2018):
| Type | Host | Value |
| CNAME | mesmtp._domainkey.{mydomain.com} |
mesmtp.{mydomain.com}.dkim.fmhosted.com |
SPF
Allows receivers to know you send your mail via Fastmail, and other servers.
| Type | Host | Value |
| TXT | {mydomain.com} |
v=spf1 include:spf.messagingengine.com ?all |
DMARC
Specifies what to do with messages that fail DKIM and SPF.
| Type | Host | Value |
| TXT | _dmarc.{mydomain.com} |
v=DMARC1; p=none; |
Client email auto-discovery
Allows email clients to automatically find the correct settings for your account.
| Type | Host | Priority | Weight | Port | Target |
| SRV | _submission._tcp.{mydomain.com} |
0 |
0 |
0 |
. |
| SRV | _submissions._tcp.{mydomain.com} |
0 |
1 |
465 |
smtp.fastmail.com |
| SRV | _imap._tcp.{mydomain.com} |
0 |
0 |
0 |
. |
| SRV | _imaps._tcp.{mydomain.com} |
0 |
1 |
993 |
imap.fastmail.com |
| SRV | _pop3._tcp.{mydomain.com} |
0 |
0 |
0 |
. |
| SRV | _pop3s._tcp.{mydomain.com} |
10 |
1 |
995 |
pop.fastmail.com |
| SRV | _jmap._tcp.{mydomain.com} |
0 |
1 |
443 |
api.fastmail.com |
| SRV | _autodiscover._tcp.{mydomain.com} |
0 |
1 |
443 |
autodiscover.fastmail.com |
Client CardDAV auto-discovery
Allows CardDAV clients to automatically find the correct settings for your account.
| Type | Host | Priority | Weight | Port | Target |
| SRV | _carddav._tcp.{mydomain.com} |
0 |
0 |
0 |
. |
| SRV | _carddavs._tcp.{mydomain.com} |
0 |
1 |
443 |
carddav.fastmail.com |
Client CalDAV auto-discovery
Allows CalDAV clients to automatically find the correct settings for your account.
| Type | Host | Priority | Weight | Port | Target |
| SRV | _caldav._tcp.{mydomain.com} |
0 |
0 |
0 |
. |
| SRV | _caldavs._tcp.{mydomain.com} |
0 |
1 |
443 |
caldav.fastmail.com |