Mail Domains¶

Every Asteroid gets its own mail domain in the form of $USER.uber.space. You can setup as many additional domains as you like.

We don't sell domains

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 Asteroid.

Add a domain¶

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

[isabell@moondust.uberspace.de ~]$ uberspace mail domain add isabell.example
OK: Added maildomain 'isabell.example' to your Asteroid

Use the following values for your DNS:

$ORIGIN isabell.example.
@                      IN  MX     in-mx.uberspace.de.
@                      IN  TXT    "v=spf1 include:spf.uberspace.de ~all"
@                      IN  TXT    uberspace-mail-PhUlYkQ1S8
uberspace1._domainkey  IN  CNAME  dkim1.uberspace.de.
uberspace2._domainkey  IN  CNAME  dkim2.uberspace.de.

The output of this command uses the zone file format to show the proposed records for your domain.

Add an alias domain¶

You can setup domains to be alias domains of domains you already added to additionally receive, send and access mail with the alias domain. All mailboxes with the original domain will also work with the alias domain:

[isabell@moondust ~] $ uberspace mail domain add klaus.example --alias-of isabell.example
OK: Added maildomain 'klaus.example' to your Asteroid

Use the following values for your DNS:

$ORIGIN klaus.example.
@                      IN  MX     in-mx.uberspace.de.
@                      IN  TXT    "v=spf1 include:spf.uberspace.de ~all"
@                      IN  TXT    uberspace-mail-mqD3BgKp8
uberspace1._domainkey  IN  CNAME  dkim1.uberspace.de.
uberspace2._domainkey  IN  CNAME  dkim2.uberspace.de.

DNS records¶

Several records need to be configured in your domain registrar’s nameserver:

MXSPFDKIMDNS TXT

The MX record is the primary record for your mail domain setup. It should point directly to in-mx.uberspace.de.. It tells other mailservers, to contact this host for transmitting mail to your domain.

Type	Name	Value
MX	`@`	`in-mx.uberspace.de.`

The trailing dot

Please be aware that the trailing dot in in-mx.uberspace.de. 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.

A SPF record makes sure that only specific mailservers are allowed to send mail from your domain.

Type	Name	Value
TXT	`@`	`"v=spf1 include:spf.uberspace.de ~all"`

You can of course adjust those settings if you know what you do.

Quoting

Please be aware that your domain hoster UI might set the quotes around the value itself. In this case you should leave them out.

DKIM is an additional security method that signs the FROM part of your mail with a specific private key.

Type	Name	Value
CNAME	`uberspace1._domainkey`	`dkim1.uberspace.de.`
CNAME	`uberspace2._domainkey`	`dkim2.uberspace.de.`

This TXT record is an additional randomly generated validation token which helps us verify that you own the domain.

Type	Name	Value
TXT	`@`	`uberspace-mail-PhUlYkQ1S8`

List your domains¶

If you want to find out which domains are currently set up for mail on your Asteroid and their DNS validation state, use the uberspace tool:

[isabell@moondust ~]$ uberspace mail domain list

  Domain                Alias of           DNS state
 ───────────────────────────────────────────────────────
  isabell.example                          VALID
  klaus.example         isabell.example    UNCHECKED
  isabell.uber.space                       VALID

DNS Validation¶

When you add a mail domain, you're shown the proposed DNS records containing a randomly generated validation token. Every 5 minutes we validate if the mail domain you added to your Asteroid was properly configured with the validation token at your DNS provider. Your mail domain remains disabled unless validation is successful. Once validated, your domain stays validated until you remove the domain.

To output the DNS validation state and the proposed DNS records, including the validation token, use the uberspace tool:

[isabell@moondust ~]$ uberspace mail domain show isabell.example

 Domain: isabell.example
 DNS state: UNCHECKED

Use the following values for your DNS:

$ORIGIN isabell.example.
@                      IN  MX     in-mx.uberspace.de.
@                      IN  TXT    "v=spf1 include:spf.uberspace.de ~all"
@                      IN  TXT    uberspace-mail-PhUlYkQ1S8
uberspace1._domainkey  IN  CNAME  dkim1.uberspace.de.
uberspace2._domainkey  IN  CNAME  dkim2.uberspace.de.

Validation Token

Instead of the randomly generated validation token you can also use uberspace-mail-ASTEROID_NAME i.e. uberspace-mail-isabell as a validation token for all you mail domains. It's easier but offers less privacy.

Remove a domain¶

To remove a domain, use the uberspace tool:

[isabell@moondust ~]$ uberspace mail domain del isabell.example
OK: Removed maildomain 'isabell.example' from your Asteroid

Warning:

This will delete all aliases, forwards and mailboxes for this domain.

Debugging¶

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

[localuser@localhost ~]$ dig MX isabell.example +short
0 in-mx.uberspace.de.
[localuser@localhost ~]$ dig TXT isabell.example +short | grep spf
"v=spf1 include:spf.uberspace.de ~all"
[localuser@localhost ~]$ dig TXT isabell.example +short | grep uberspace-mail
uberspace-mail-PhUlYkQ1S8
[localuser@localhost ~]$ dig CNAME uberspace1._domainkey.isabell.example +short
dkim1.uberspace.de.
[localuser@localhost ~]$ dig CNAME uberspace2._domainkey.isabell.example +short
dkim2.uberspace.de.
[localuser@localhost ~]$