How to set up my domain name

Customers who use a business account at mailbox.org need to set up a domain name for their account before it can be used. The first step is to add a security key to the domain: Log in to your administration interface at https://setup.mailbox.org, click on the „+“ symbol and enter the domain name into the corresponding form field. (without the „www.“). After clicking on „Generate Security Key“, a warning message will appear that complains about a missing security key. However, note that the key information you will need in the next step is displayed as part of the message!
Please go to the domain administration page of the organization that is your domain provider (not mailbox.org) and create a DNS entry with the displayed key information. To do this, create the sub-domain exactly like the one displayed in the warning message as „Hostname“ and set a „TXT record“ for that sub-domain with the given security key set as value.

Once the security key has been set up in your domain provider's DNS, you can go back to the mailbox.org administration interface and add the domain to your account. However, note that due to the way DNS information is distributed across the Internet, it may take up to 24 hours for the changes you made at the domain provider to be verifiable by our servers. It often works a lot faster than this but you will only be able to proceed with the next step once verification has been completed successfully

After successfully adding a domain name to your mailbox.org account, it is necessary to adjust the MX records for your domain at the DNS (Again, at your domain provider) to exclusively point to mailbox.org.

Please set the following MX records in your DNS administration and before you do, replace “example.net” with your own domain name:

example.net. IN MX 10 mxext1.mailbox.org. example.net. IN MX 10 mxext2.mailbox.org. example.net. IN MX 20 mxext3.mailbox.org.

Important: As soon as the MX records have been set to point to our servers as stated, all incoming e-mails will go directly to mailbox.org. It is very important that the corresponding e-mail addresses exist on our systems before this happens. If they do not, our systems will reject any messages sent to those e-mail addresses (“Undeliverable – User unknown”). Therefore, make sure to create your required inboxes and/or aliases first, and then make the necessary changes to the MX records as described above.
Tip: The easiest way to receive all e-mails for those addresses that have not been associated with an inbox yet is to create a single „catch-all“ inbox for the domain. However, expect to receive more spam and also check if the application of filter rules is an option for you in such a scenario.

Improving spam-reputation

Please also consider setting up SPF, DKIM and DMARC DNS records. You may find the respective points in this guide for private clients useful.
As a business customer the same applies for you.
Setting up those records is going to increase the spam reputation of your domain significantly.