DKIM + ARC Record

Basics

The ARC/DKIM record for a domain is automatically created and can be retrieved in the mailcow Groupware panel.

Since ARC and DKIM use the same key, it is sufficient to add a single "domainkey" TXT record in the DNS. To obtain the corresponding entry, simply click "open" under the "Domains" table in the mailcow panel to view the details of the desired domain.

The "Canonicalization" of mailcow is always set to "relaxed/relaxed", which means that minor differences in the formatting of the email, such as additional spaces or line breaks, are ignored.

Did you know?

DKIM (DomainKeys Identified Mail) is used to ensure the authenticity of emails and to verify that they have not been tampered with during transmission. This is achieved through a digital signature in the email header, which can be verified by the recipient using the domain's public key. The public key is stored as a TXT record in the DNS, making it accessible for verification.

Example DNS Configuration

An example of the DNS configuration for a DKIM record could look like this:

domainkey._domainkey.example.com. IN TXT "v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQ..."

Here, domainkey is the name of the DKIM key, example.com is the domain, and the value of the TXT record contains the public key used for verification.

---

Where can I find the ARC/DKIM key in mailcow Groupware?

To find the ARC/DKIM key or the corresponding DNS records, you need to log in as a domain administrator. You can find instructions for this here.

Once logged in, you can view the ARC/DKIM information by clicking edit for the respective domain: