Mail Domains

Every Uberspace account gets its own mail domain in the form of $ You can setup as many additional domains as you like.


Uberspace is strictly a hosting provider, which is why we don’t offer domain registrations. You can, of course, use any domain that you registered with an external domain provider with your Uberspace account. At the end of this article is a list of some popular domain providers.


In order to use your own domain for mail with your Uberspace, you need to first set it up using our uberspace tool:

[isabell@stardust ~]$ uberspace mail domain add
The mailserver's configuration has been adapted.
Now you can use the following records for your DNS:                      IN   MX 0                      IN  TXT "v=spf1 ~all" IN  TXT "v=DKIM1;t=s;n=core;p=MIICIj...=="

The trailing dot may be skipped, if the interface does not accept it.

Once you’ve set up your domain using the uberspace tool you will be provided with several records that need to be configured in your domain registrar’s nameserver.


You can only add fully qualified domain names (FQDNs), wildcard domains are not available.


Please be aware that the trailing dot in is the correct notation of a DNS record to indicate the domains root like here, but you can skip it if the domain hoster UI does not accept it.

Domain records

You can get the correct DNS records anytime after setup with uberspace records show

[isabell@stardust ~]$ uberspace records show
@                    IN   MX 0
@                    IN  TXT "v=spf1 ~all"
uberspace._domainkey IN  TXT "v=DKIM1;t=s;n=core;p=MIICIj...=="

The output of this command uses the zone file format to show the proposed records for your domain. In the following we provide some short explanations of those records:

MX record

The MX record is the primary record for your mail domain setup. It should point directly to your hostname like It tells other mailservers, to contact this host for transmitting mails to your domain.

SPF record

You should set a SPF record to make sure that only specific mailservers are allowed to send mails for your domain.


Some mailproviders like GMail are even blocking mails when there is no SPF record provided for the sending domain.

We provide a list of our allowed mailservers and you will need to add a TXT record with the content v=spf1 ~all to your domain to include it. You can of course adjust those settings if you know what you do.

DKIM record

DKIM is an additional security method that signs the FROM part of your mail with a specific private key. Each Uberspace has its own private/public key pair, you will need to add the public key to your domain records to make use of this.

You will need to add a TXT record to the subdomain with the content of your public DKIM key in the format v=DKIM1;t=s;n=core;p=MIICIj(quite-long-multiple-chars)...==.


At the record subdomain is the part that other mailservers will look up for dkim key selectors and uberspace is the selector we use when sending out mails via smtp.

Check your records

To check if you have successfully configured your domain records, you can use the commands below:


Because the records are set up in your custom domain (here you can check from any system if they are correct. But keep in mind, that the DNS system may need a while – depending on the previous record’s Time to Live (TTL) value – to refresh after you adjusted your records.

check MX record

$ dig MX +short

This should return your hostname which would be different to stardust.

check SPF record

$ dig TXT +short | grep spf
"v=spf1 ~all"

This should return the given output by default.

check DKIM record

$ dig TXT +short
"v=DKIM1;t=s;n=core;p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA1xE5uMU/BgC4djxbCvxTHOUxttAY5TF73TEqyLHrRIBkcrut6K7hM3rvmkNxct85oo/4ZJQN0k/SIW9p88WKymD6iWEaGa6ia0ZgF+qCVa7bB/rLYtPbbI4jVmcAZ1g+x2jiLZCG3lCGf5mOQaM5OaXw+L3si2bHgEK2S+CCJQRFgS4ewatGJAjarJXaJW" "7f1wnMTr+usRw7VQ/u2019zCV2eKnFWoJO+5fH7O+hI5QmXj58dFK7IzhkRBWLJq+sz60k0FSPTFQmJ31u00i0zNRY8FX6Zh7LKFBo5ILcue4v1kVOJCyHqQg3Bx1MK6FKG2kFHWTCha+WkOtx85ihCwIDAQAB"

The output should look similar to this but with different chars for your personal key after p=.

Domain validation

We will frequently validate that the MX record of your domain is really set up to the corresponding host with The automated check will run normally every 30 seconds to lookup the DNS records of the domains you added to your account. If the correct value is missing this will be shown as an error next to the specific domain listing:

[isabell@stardust ~]$ uberspace mail domain list DNS INVALID (checked 2021-08-20 12:00)

Until this check has passed successfully, you will not be able to use this domain for receiving mails or to login to your mailbox. After a failed check, this domain will be checked again only after 3 minutes.


To get the most accurate record value, we check the responsible domain nameserver directly. But nevertheless it can take some minutes for the correct data to show up after you set up the records at your domain hoster. You can check yourself with dig MX +short if the host already gets the correct values.


If you want to find out which domains are currently set up for the mail server on your Uberspace account, use the uberspace command:

[isabell@stardust ~]$ uberspace mail domain list

This will list all domains and sub-domains currently set up for this account, including the default $


To remove a domain, use the uberspace tool:

[isabell@stardust ~]$ uberspace mail domain del isabell.example
The server's configuration has been adapted.

Internationalized domains


If you want to add or remove an internationalized domain name (IDN), please use the ASCII representation (“punycode”). For example, please use instead of ü

To convert an internationalized domain name to punycode, use the idn command:

[isabell@stardust ~] $ idn ü

If locale inside your uberspace shell is not set correctly, this command can fail with a “could not convert” error message. To fix this, either configure your local terminal to use an UTF-8 locale or call idn like so: LANG=en_US.utf8 idn ....

Domain Providers