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Domains and DNS

tsmartSend sends only from domains your company has verified. Verification has two parts: proving that you own the domain, then publishing SPF and DKIM so receiving servers accept mail we send in your name.

Overview

1. Add the domain (console or POST /domains).
2. Publish the ownership TXT record and verify. The domain is then created on our mail server with a DKIM key.
3. Publish the SPF and DKIM records (and, recommended, DMARC) and check again.
4. When SPF and DKIM are both in place, the domain's status is verified and it can send.

A domain that is already used for mailboxes on tsmart.ai has gone through steps 1 and 2; it only needs SPF and DKIM. You can verify a subdomain (for example notify.acme.com) and send application mail from it, keeping it apart from the mail your people send.

1. Add the domain

In the console open Account → Domains → Manage domains, or call the API with a full-access key whose creator has the Domains privilege:

curl -X POST https://send.tsmart.ai/domains \
  -H "Authorization: Bearer $TSMART_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"name": "acme.com"}'

{
  "object": "domain",
  "id": "b7c1e0a2-5d0f-4a51-9a64-0f3c2a7d9e11",
  "name": "acme.com",
  "status": "not_started",
  "created_at": "2026-10-12 09:30:11.412000+00",
  "region": "eu-central",
  "capabilities": { "sending": "disabled", "receiving": "disabled" },
  "open_tracking": false,
  "click_tracking": false,
  "records": [
    {
      "record": "Ownership",
      "name": "_tsmart-verify.acme.com",
      "type": "TXT",
      "ttl": "Auto",
      "status": "pending",
      "value": "tsmart-verify=Vb3kQ9mXf2LpT7wRzA1c_8nE"
    }
  ]
}

const { data, error } = await tsmart.domains.create({ name: "acme.com" });

domain = client.domains.create({"name": "acme.com"})

Rules when adding a domain:

• A domain can belong to only one company. A name that is already registered is refused.
• Public mailbox providers and reserved example domains cannot be added.
• A company can have at most 10 domains waiting for ownership verification, and its plan may limit the total.
• A domain whose ownership is not proven within 7 days of when your company first added it is removed; add it again to get a new token. Deleting the domain and adding it again does not restart the 7 days.
• While another company's unproven claim holds a domain, adding it is refused with the date from which it can be added if that company does not prove ownership. A company whose claim lapsed while another company was waiting for the domain cannot add it again for the next 7 days, so the waiting company can take it.

2. Prove ownership

Publish one TXT record with the token from the console or from records:

Then click Verify on the domain page, or call POST /domains/{id}/verify. If the record is not found yet, the API answers 422 validation_error with The TXT record _tsmart-verify.acme.com was not found yet. The check asks the domain's own name servers, so a record you just published is usually seen at once.

curl -X POST https://send.tsmart.ai/domains/b7c1e0a2-5d0f-4a51-9a64-0f3c2a7d9e11/verify \
  -H "Authorization: Bearer $TSMART_API_KEY"

When ownership is proven, the domain is created on our mail server together with its DKIM key, and the DNS records below are listed. You can delete the _tsmart-verify record afterwards.

If the company owner has connected a supported DNS provider account in the console, the domain page can publish the ownership record and the missing records for you.

3. Publish the sending records

The console's domain page and GET /domains/{id} list the exact values for your domain. SPF and DKIM are required; DMARC is recommended.

SPF

SPF tells receiving servers that our mail server may send for your domain. It is a TXT record on the domain itself.

• Keep a single SPF record. If you already have one, add ip4:91.99.133.27 right after v=spf1 and keep every other mechanism and the ending (~all or -all) as they are. The console suggests exactly this merged value.
• The check passes when the record itself contains ip4:91.99.133.27 or a:mail.tsmart.ai. It does not follow include: mechanisms, so an include that happens to cover the address does not count.
• An ip4: mechanism needs no DNS lookup, so it does not use up SPF's limit of 10 lookups.

DKIM

Every email is signed with a 2048-bit DKIM key that belongs to your domain. The public key is published as a TXT record under the domain's selector.

• The selector is ts followed by the year and month the domain was added (ts2610 for October 2026). Always use the selector and value the console or the API shows for your domain; it changes if the key is rotated.
• The key is created when ownership is proven, so the DKIM value appears only after that step. For a few moments it can show as still being generated.
• The check passes when the published record contains the key (the p= value); spaces are ignored.

DMARC (recommended)

DMARC tells receivers what to do with mail that fails SPF and DKIM, and where to send reports. It is not required to send, but large mailbox providers increasingly expect it.

With this record the aggregate reports arrive at tsmart.ai and are shown in the console under Reporting → DMARC reports. If your domain already has a DMARC record, the console keeps it as it is; do not publish a second one. Start with p=none, read the reports, then move to p=quarantine or p=reject once all your legitimate mail passes.

MX (optional, for incoming mail)

tsmartSend does not need an MX record. Publish acme.com MX 10 mail.tsmart.ai. only when the domain's mailboxes move to tsmart.ai: changing MX moves all incoming mail for the domain, so do it on the day you switch. Replies to your emails go to the from or reply_to address wherever its mailbox is hosted.

Other records for mailboxes (optional)

The console also lists records that help mail apps and other mail servers when the domain's mailboxes are on tsmart.ai. None of them affects tsmartSend.

4. Check the records

After publishing, click Check DNS records on the domain page or call POST /domains/{id}/verify again. Once ownership is proven, every call re-reads the records and stores the result; GET /domains/{id} then shows it.

{
  "object": "domain",
  "id": "b7c1e0a2-5d0f-4a51-9a64-0f3c2a7d9e11",
  "name": "acme.com",
  "status": "verified",
  "capabilities": { "sending": "enabled", "receiving": "disabled" },
  "records": [
    { "record": "SPF", "name": "acme.com", "type": "TXT", "ttl": "Auto", "status": "verified",
      "value": "v=spf1 ip4:91.99.133.27 ~all" },
    { "record": "DKIM", "name": "ts2610._domainkey.acme.com", "type": "TXT", "ttl": "Auto", "status": "verified",
      "value": "v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA…" },
    { "record": "DMARC", "name": "_dmarc.acme.com", "type": "TXT", "ttl": "Auto", "status": "pending",
      "value": "v=DMARC1; p=none; rua=mailto:reports@system.tsmart.ai; fo=1" },
    { "record": "MX", "name": "acme.com", "type": "MX", "ttl": "Auto", "status": "pending",
      "value": "mail.tsmart.ai.", "priority": 10 }
  ]
}

capabilities.sending becomes enabled as soon as ownership is proven; only status: "verified" means the domain can actually send. capabilities.receiving shows whether the domain's incoming mail is handled by tsmart.ai.

What blocks sending

The platform also re-checks the records of every verified domain regularly. If SPF or DKIM disappears, sending from the domain stops with domain_not_verified until the record is back and checked again. A record that passed before and fails is re-checked once after a short pause, so a single slow name server does not stop sending. A scheduled email whose domain is no longer ready when it comes due fails with an email.failed event.

Tracking and removal

Open and click tracking are switched per domain with PATCH /domains/{id} (open_tracking, click_tracking), both off by default; see Sending email. A domain is removed in the console or with DELETE /domains/{id}, which needs a key created by a company owner and is refused with 409 resource_in_use while the domain still has mailboxes.

Webhooks can subscribe to domain.created, domain.updated and domain.deleted; see Webhooks.