What each record does
SPF (Sender Policy Framework) is a DNS TXT record that lists which servers are allowed to send mail for your domain. Inbox providers check it against the server a message actually came from. Loops publishes its own SPF at envelope.yourdomain.com, so it does not collide with any SPF record already at your root domain.
DKIM (DomainKeys Identified Mail) adds a cryptographic signature to every message you send. Inbox providers use the matching public key, published in DNS, to confirm the message was not changed in transit. DKIM records live at selector._domainkey.yourdomain.com, so the checker probes common selectors automatically and lists any it finds. Some providers, including the infrastructure behind Loops, use randomized selectors that only appear on your own domain records page. With Loops, DKIM signing is active from your first send.
DMARC (Domain-based Message Authentication, Reporting and Conformance) tells inbox providers what to do with mail that fails SPF or DKIM. A DMARC record sits at _dmarc.yourdomain.com and carries a policy: p=none reports but still delivers, p=quarantine sends failing mail to spam, and p=reject blocks it. A DMARC record at your root domain covers your subdomains too.
MX (mail exchange) records point to the servers that receive mail for your domain. Loops includes an MX record in the set you add during domain setup. If MX is missing here, the domain is not set up to receive mail yet.
How to fix a missing record
Every record above comes from one place. In Loops, open Settings → Domain and click View records. You will see the SPF, DKIM, MX, and a default DMARC record, each with a copy button. Paste them into your DNS provider one by one, using the record Type (TXT, MX, or CNAME) rather than the label, then click Verify Records. The full walkthrough, with per-registrar notes, is in Setting up your domain.
For the authentication trio specifically, DMARC and DKIM setup covers how the records fit together and how to move your DMARC policy from p=none to p=quarantine to p=reject as your reports come back clean.
Authentication gets you past the front door. If mail still lands in spam after your records verify, the causes are usually reputation and list quality. See why emails go to spam and the broader email deliverability guide.