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DNS (Domain Name System) is the system used on the internet to translate domain names (e.g. www.example.com, fastmail.fm, etc) to actual machines to contact. The process of converting a domain name to a machine to contact is called a "lookup".
Each domain can have multiple different result types for a lookup, called record types. The three most common record types are NS records, A records and MX records.
DNS also allows other record types such as SOA, TXT, PTR and SRV records used for various other less commonly used services.
DNS can be a confusing and complicated system. If you get something wrong, you can bounce email for your domain, or cause your domains website to stop working, and it can take hours or days to fix. For that reason, unless you understand what you're doing, or have been instructed explicitly by someone who knows what they're doing, we recommend that you don't modify the DNS for your domain.
Having said that, if you know exactly what you want to do, then the Custom DNS screen will let you create arbitrary DNS A, MX, etc records for your domain or sub-domains.
The Custom DNS screen allows you to specify exactly what DNS records to publish for your domains you have setup at FastMail.FM.
This allows you to:
There are two things you need to do:
Once these steps are done, we will publish default DNS records for your domain. You can then use the Custom DNS screen to change the DNS records for your domain to whatever you want.
If you don't specify custom DNS settings for a domain, then our name servers will publish the following records for your domain.
yourdomain.com Type=MX TTL=3600 STANDARD_MX (standard email - e.g. user@yourdomain.com)
*.yourdomain.com Type=MX TTL=3600 STANDARD_MX (subdomain addressed email - e.g. user@mail.yourdomain.com)
yourdomain.com Type=A TTL=3600 STANDARD_WEB (main website - http://yourdomain.com/)
*.yourdomain.com Type=A TTL=3600 STANDARD_WEB (subdomain websites - including http://www.yourdomain.com/)
mail.yourdomain.com Type=A TTL=3600 STANDARD_MAIL (webmail login - http://mail.yourdomain.com/)
yourdomain.com Type=CSV TTL=3600 CSV_DENY_ALL (no email sending machines identify as yourdomain.com)
These records are suitable for most users.
The meaning of STANDARD_MX, STANDARD_WEB and STANDARD_MAIL are described here.
Normally when specifying A records you have to specify an IP address, and for MX records you have to specify a priority and a host. For standard FastMail.FM services however, you can use the special mnemonics STANDARD_MX, STANDARD_WEB and STANDARD_MAIL.
There's also another special name, STANDARD_SPF, which can be use for generating SPF records which say "mail is only sent via FastMail.FM". We don't add these by default because many people send outbound email via their ISP or work email systems as well.
By using these mnemonics, you avoid the need for hardcoding particular IPs/hostnames in case they should change in the future.
Currently we support creating A, MX, CSV, CNAME, SRV, TXT and SPF records. We may add more in the future.
Yes. Just setup the domain as described, and change the Routing column to Force Ext. The domain will stay in the Force Ext state and email will never be captured locally, but the DNS records you setup will be published by our nameservers.