Domains & DNS

To use your own domain with Cirrux, you need to add a few DNS records at your domain registrar. This page explains what each record does and provides the values you need.

You can also find these records in your Workspace settings → Domains after adding a domain, where domain-specific values (like DKIM keys) are generated for you.

MX records

MX (Mail Exchange) records tell other mail servers where to deliver email for your domain. You need two MX records: a primary server and a backup that accepts mail when the primary is temporarily unreachable.

The trailing dot marks a fully qualified domain name. Most DNS providers require it, but some add it automatically. If your provider doesn't accept the dot, you can safely leave it off.

Receiving email on a subdomain

If you already have a domain set up in Cirrux (e.g. example.com), you can also receive email on a subdomain like mail.example.com or invoices.example.com. This is useful when you want to receive mail at a dedicated subdomain, for example to give out to services that send invoices or notifications.

To set this up, add MX records for the subdomain. Use the subdomain as the host instead of @:

Replace invoices with your actual subdomain. Some DNS providers also support using * as a wildcard host, which routes email for all subdomains to Cirrux at once. No additional DNS records (SPF, DKIM, etc.) are needed — the subdomain inherits those from your main domain. Note that sending email from a subdomain is not currently supported.

SPF record

SPF (Sender Policy Framework) tells receiving mail servers which servers are allowed to send email on behalf of your domain. This helps prevent spoofing and improves deliverability.

If you already have an SPF record for your domain, add include:_spf.cirrux.co to your existing record instead of creating a new one. A domain can only have one SPF record.

DKIM records

DKIM (DomainKeys Identified Mail) adds a cryptographic signature to outgoing emails, allowing receivers to verify that the message was actually sent by your domain and hasn't been tampered with. Cirrux generates three DKIM keys for each domain.

The easiest way to set up DKIM is with CNAME records, which point to Cirrux-hosted keys. This means you don't need to update your DNS if we rotate keys in the future. Alternatively, you can copy the full TXT values directly.

The exact selector names and values are shown in your domain settings after adding the domain to Cirrux. The trailing dot marks a fully qualified domain name. Most DNS providers require it, but some add it automatically. If your provider doesn't accept the dot, you can safely leave it off.

DMARC record

DMARC (Domain-based Message Authentication, Reporting and Conformance) builds on SPF and DKIM. It tells receiving servers what to do when an email fails authentication, and where to send reports. The recommended policy is reject, which means unauthenticated emails are rejected entirely.

Domain verification

When you add a domain, Cirrux asks you to create a TXT record to prove you own the domain. This verification token is unique to your workspace.

Your verification token is shown in Workspace settings → Domains after adding the domain.