A, AAAA, CNAME, MX and TXT explained
DNS connects your domain to websites, email and other services. Each record has its own job.
Read guide ↗The essentials
Register the domain, choose a separate email service and create a mailbox there. Then enter its DNS records in the active DNS zone. atdomain.at provides domain and DNS management, but does not sell mailboxes.
1. A domain and an existing contact mailbox
You can use a domain for email without running a website. Decide whether to share a personal address, office@ or a dedicated support address. For the domain account itself, start with an independent mailbox that already works. This keeps you reachable before setup and if the domain’s mail service later has a problem. Do not advertise a mailbox as active before testing it.
2. Choose a mail service and create the mailbox
Choose a mail service that supports custom domains and the mailboxes, storage and devices you need. Check whether an address is only a forwarding alias or a mailbox that can also send mail. An existing personal account does not automatically support a custom domain. Create the intended addresses there and secure access. The mail service’s charges are separate from domain registration.
3. Enter records in the active DNS zone
Your mail service supplies the required DNS values. With atdomain.at’s default nameservers, edit records in your account. With custom nameservers, use your chosen DNS service’s active zone. Copy names, destinations and priorities accurately. Leave website records intact unless a change is required. When moving an existing mail service, save its current records and prepare the new mailboxes before replacing MX records.
A, CNAME, MX and TXT in detail ↗4. Distinguish delivery from sender authentication
MX records direct incoming mail. SPF identifies permitted sending sources. DKIM uses a signature that can be checked against published DNS information. DMARC adds policy and reporting for sender authentication. These records do not replace a mailbox or guarantee inbox placement. Follow your mail service’s instructions rather than copying arbitrary examples. If several services send mail using your domain, their configuration needs to be considered together.
5. Test both directions after the change
Send a message from an independent mailbox to the new address and reply to it. Then test another external service, check spam folders and, where available, authentication results in message headers. Testing only within the same mail service is insufficient. DNS caches may temporarily keep old MX destinations during a change. When moving services, keep the previous mailbox accessible for a transition period and watch for messages still arriving there.
Further sourcesIETF: SPF for email sending (RFC 7208) ↗IETF: DNS records and their functions (RFC 1035) ↗