Sending domains and DNS

Before you can use a domain as the sender of your email, you add it to a mail server, prove that you own it, and publish authentication records in DNS. Correct SPF, DKIM and DMARC records make receiving servers more likely to trust your mail and keep it out of spam folders.

#Prerequisites

• A Transactional Mail subscription with status Active.
• At least one mail server in the subscription. If you don't have one yet, open the subscription, go to the Mail Servers tab, create a server, enter a Server Name and choose Live (Production) or Development (Testing) as the Mode.
• Access to edit the domain's DNS records, either in Yeap Cloud DNS or at another DNS provider.

#Add a domain

1. Open My Email Services (/tm/subscriptions) and click the subscription name to open it.
2. Go to the Domains tab and click Add Domain in the top-right corner.
3. Fill in the form:
   • Mail Server: the mail server the domain belongs to.
   • Domain Name: for example example.com. The form currently accepts only a name plus a top-level domain (such as example.com). Multi-level names such as mail.example.com are rejected.
   • Verification Method: choose DNS Record.
4. Confirm. The domain appears in the list and the Verified column shows Pending.

To see another mail server's domains, pick it from the drop-down above the list.

#See the records you need

Click DNS on the domain's row. The DNS Records for <domain> panel opens on the right. It lists each record's type, Name, value and, for MX, its Priority. Every value has a copy button next to it.

The records follow these formats:

Notes:

• DKIM: the key pair is generated automatically when you add the domain, and every domain gets its own. The DNS panel shows the full record name and public key, so copy them exactly. The key is long. If your DNS provider limits the length of a single TXT string, use the provider's long-TXT method (several quoted strings) and don't shorten the key.
• Ownership verification TXT: the value starts with postal-verification, followed by a token unique to the domain. Add it at the domain apex (@). If the DNS panel doesn't list this record, contact support for the verification token.
• MX: you only need this to receive inbound mail through Transactional Mail. If the domain already receives mail through another service, including Yeap Cloud Domain Mailbox, do not change its existing MX records. Changing them will disrupt normal mail delivery.

#SPF: keep a single record

A domain can have only one v=spf1 record. If the domain already has one (for example for your company mailbox), don't add a second record. Merge the mechanism Transactional Mail needs (include: or a:) into the existing record instead, for example:

v=spf1 mx include:<existing service> include:<value from Transactional Mail> ~all

When a domain has two SPF records, many receivers treat SPF as failed.

#DMARC

The console doesn't generate a DMARC record. We recommend adding a TXT record at _dmarc.example.com. Start with a policy that only monitors and doesn't block:

_dmarc.example.com.  TXT  "v=DMARC1; p=none; rua=mailto:dmarc-reports@example.com"

Watch the reports for a while. Once SPF and DKIM pass reliably, tighten the policy to p=quarantine or p=reject. A domain can also have only one DMARC record, so if you already have one, edit it instead of adding another.

#Verify the domain

1. Add the records at your DNS provider and wait for them to propagate. This can take a few minutes or several hours, depending on the provider and the TTL.
2. Return to the Domains list and click Verify on the domain.
3. The platform looks up the TXT records at the domain apex for postal-verification <verification token>:
   • If the record is found, you see Domain verified and the Verified column changes to Verified.
   • If it isn't found, you get a DNS verification error ("DNS verification failed. Please add TXT record."). Check that the record is at the apex and the value is complete, then try again later.

You can check from the command line that the records are live:

dig +short TXT example.com
dig +short TXT postal-<identifier>._domainkey.example.com
dig +short TXT _dmarc.example.com

#Delete a domain

Click the delete button on the domain's row and confirm Delete this domain?. The domain is removed from the mail server and can no longer be used as a sender. Its DNS records aren't removed automatically, so delete them at your DNS provider.

#Related

• Transactional Mail overview
• SMTP and API