Add a sending domain to SMTP Relay

An SMTP Relay sends only from domains you have shown are yours. Add the domain your application sends from, publish its records and verify it. The relay adds no MX record, so the domain's inbox stays wherever it is.

• An SMTP Relay service with the status active. Order one if you have none. While a service is being set up, Add domain… is greyed out.
• A domain whose DNS you can change. When its zone is on Coritan DNS in the same account, we publish the records for you.
• Room on the plan. The Domains card shows the plan's limit, such as 1 of 2 on this plan., or The domains your applications send from. when the plan has no limit.
• If the domain is on your Mail Hosting service, a sending subdomain for the relay, such as send.example.com. A domain can be on one mail service at a time, and the relay can still send as @example.com over SMTP.

1. In the dashboard, go to Email, open the SMTP Relay service, then the Domains tab.
2. Select Add domain….
3. In Domain, enter the domain, such as example.com or send.example.com. Names you claimed under coritan.gg are listed beside Your names:.
4. Leave Make this the primary domain ticked if this is the relay's main domain. The primary domain names the relay in lists.
5. Select Add domain.

The domain's page opens, with its records on the DNS records card: the ownership record, SPF, two DKIM records once ownership passes, and DMARC.

When the domain's zone is on Coritan DNS in this account, or the domain is a claimed coritan.gg name, we have already published the records. When the zone is on Coritan DNS but was added to this account after the domain, use the Publish to your zone card on the domain's page.

At any other DNS provider:

1. Create the ownership record: the TXT record at _mailverify.example.com. Copy its name and value from the DNS records card.
2. Create the SPF record. If the domain already has one because another service sends for it, add include:_spf.<base> from the card to that record instead of creating a second one.
3. Create the DMARC record at _dmarc.example.com.
4. On the domain's page, select Verify now. Once we find the ownership record, we make the domain's two DKIM keys.
5. Reload the page, then create the two DKIM records it now lists.

Mail DNS records explains each record and what its check looks for.

1. On the domain's page, select Verify now.
2. Read the toast. example.com is verified. means you are done. example.com is still pending: is followed by the first problem the check found.
3. If it is still pending, fix what the Checks row and the The last check found problems list show, and select Verify now again.

We also check pending domains about every ten minutes, so a domain whose records are right verifies on its own.

• The domain shows Verified on the Domains tab, with Ownership, SPF and DKIM ticked. DMARC is shown too, but a domain is verified without it.
• The Send tab and the send API accept From addresses on the domain.
• When we publish into your zone, the page shows Ready: the records are in your zone, with Open Credentials.

Next, create an SMTP credential. The relay needs one for SMTP and for the send API.

1. Delete the SMTP credentials on the domain first. See Send over SMTP with credentials.
2. On the Domains tab, select the domain.
3. In the Remove this domain card, select Remove domain….
4. Type the domain name to confirm, then select Remove domain.

We delete the records we published into a hosted zone. Records at another DNS provider are yours to delete.

Add domain… is greyed out

The service is not active yet, or the plan's domains are all used. A full plan shows This plan allows 2 domains. Remove one or change the plan to add another. Remove a domain or move to a bigger plan.

example.com receives mail on your Mail Hosting service. Add a sending subdomain here instead, such as send.example.com. Your relay can still send as @example.com.

Add send.example.com instead. Over SMTP, the relay may still write @example.com in From, because the same account has proved that domain on Mail Hosting.

example.com is already on another of your mail services

Remove it from your other SMTP Relay service first, or use a different sending subdomain.

That domain is already attached to a mail service

Someone else's mail service has it. If the domain is yours, contact support.

This plan allows 2 domain(s) or A mail service may hold at most 1000 domains

The plan, or the limit for a plan with no domain limit, is reached. Remove a domain or move to a bigger plan.

MX points to followed by other hosts

The relay does not use MX records, so this is information only: the domain can be verified with it. It shows when the domain receives its mail somewhere else.

DKIM selector cor202609r not published

The DKIM record with that selector is missing or holds a different key. Copy the whole value from the card again.

No DKIM keys yet: the mail engine has not made them

We have not finished making the domain's keys. Select Verify now again in a minute.

DMARC publishes p=reject, expected p=none

The domain already had a DMARC record with a different stage. Keep yours and set the same stage on the domain's DMARC policy card, or change your record. See DMARC.

The zone is busy with another change. Check the domain again in a minute.

Another change to the same zone was being saved. Select Verify now again.

Remove the mailboxes and aliases on this domain first

On a relay, this means the domain still has SMTP credentials. Delete them, then remove the domain.

Add a domain to Mail Hosting lists the messages both products share, such as an invalid name or a platform domain.

• Mail DNS records
• Send over SMTP with credentials
• Send email over HTTPS
• How the DMARC stage ramp works

Add a sending domain:

curl -X POST https://api.coritan.com/api/v1/client/smtp-relay/4812/domains \
  -H "Authorization: Bearer $CORITAN_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"domain": "send.example.com"}'

domain is the name (3–253 characters) and primary defaults to false. The answer is 201 with the domain and its records. A name the service refuses answers 400 with one of the messages above, and a service that is not active answers 409 Service is not active.

The other domain operations work as they do for Mail Hosting, with /client/smtp-relay/ in the path:

A domain that is not on the service answers 404 Domain not found.