Custom domains

New inboxes get an address on homingbox.net; inboxes created before 26 September 2026 keep their agents.agentboxd.com address. Temporary inboxes use tmp.agentboxd.com, and you can use your own domain on every plan. Connect a domain you own and your agents can use addresses on it instead. Mail to it arrives at our MX; mail from it is DKIM-signed with the domain’s own key.

#Use a subdomain

Connect something like mail.yourcompany.com, not yourcompany.com. To receive mail, a domain’s MX record has to point to us. On your main domain that would replace the MX your current email provider uses, so every email to @yourcompany.com, your team’s included, would come to Agentboxd, and addresses without an inbox here would bounce. A subdomain has its own MX, so nothing changes for the mail you already get.

#Add the domain

In the dashboard go to Domains and choose Add domain, or call the API. Leave receiving on (the default) if inboxes on the domain should get mail.

curl -s https://api.agentboxd.com/v1/domains \
  -H "Authorization: Bearer $AGENTBOXD_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"domain":"mail.yourcompany.com","receiving":true}'

The response has status: "pending" and the records to publish.

#DNS records

Import them all at once

If your DNS provider imports zone files (Cloudflare and Amazon Route 53 do, among others), you don’t have to add the records one by one. Press Download zone file on the domain’s page, or call GET /v1/domains/:id/zone-file, and import the file. It has one line per record to publish, with full names, and the long DKIM value already split the way DNS wants it.

curl -s https://api.agentboxd.com/v1/domains/$DOMAIN_ID/zone-file \
  -H "Authorization: Bearer $AGENTBOXD_API_KEY" | jq -r .content > mail.yourcompany.com.zone.txt

The exact token and key are on the domain’s page in the dashboard, with copy buttons. Each record in the API looks like { key, type, name, value, required, status, found? }, where status is ok, missing or mismatch and found lists what we saw instead.

• SPF: a name can have only one SPF record. If yours already has one, add include:homingbox.net to it instead of adding a second. A domain connected earlier with include:agents.agentboxd.com keeps verifying; nothing to change.
• DKIM: the p= value must match exactly. Paste it in one piece; if your provider splits long TXT values into several strings, that’s fine.
• MX: the check passes when the lowest-priority MX host is mx.agentboxd.com.

#At your DNS provider

Every provider has an “add record” form with a type, a name (or host) and a value. Many of them append your domain to the name automatically: then enter only the host part. For mail.yourcompany.com, the verification record’s host part is _agentboxd.mail and the MX host part is mail. Paste the full name into a field like that and the record ends up at _agentboxd.mail.yourcompany.com.yourcompany.com, which our check reports as missing.

The dashboard reads your domain’s nameservers to tell where its DNS is hosted, opens that provider’s steps and shows every record’s host part relative to the real zone. The API returns the same as dns on the domain ({ zone, nameservers, provider: { id, name } | null, checked_at }) and host on each record. If a record is missing but we find it under the doubled name, it carries hint: "full_name_in_host": rename it to its host part.

Cloudflare

• Open the yourcompany.com zone, go to DNS → Records and choose Add record.
• Add a TXT record: Name _agentboxd.mail, Content the record’s value. Repeat for each TXT record, with its own host part.
• Add an MX record: Name mail, Mail server mx.agentboxd.com, Priority 10.
• Paste long values such as the DKIM key in one piece: Cloudflare adds the quotes and splits values over 255 characters itself.
• TXT and MX records are never proxied, so there is no proxy setting to change.
• Source: Cloudflare’s help, checked 2026-09-27.

GoDaddy

• In your Domain Portfolio select yourcompany.com to open Domain Settings, then choose DNS and Add New Record.
• Add a TXT record: Name _agentboxd.mail, Value the record’s value. Repeat for each TXT record, with its own host part.
• Add an MX record: Name mail, Value mx.agentboxd.com, Priority 10.
• A value can be up to 1,024 characters, so paste the DKIM key in one piece.
• GoDaddy warns that changing MX records can interrupt email already connected to the domain. An MX record on a subdomain such as mail only concerns mail to that subdomain.
• Source: GoDaddy’s help, checked 2026-09-27.

Namecheap

• In your Domain List choose Manage next to yourcompany.com, then Advanced DNS. TXT records go under Host Records → Add New Record.
• Add a TXT record: Host _agentboxd.mail, Value the record’s value. Repeat for each TXT record, with its own host part.
• Add an MX record: Host mail, Value mx.agentboxd.com, Priority 10.
• Click Save all changes.
• MX records go under Mail Settings: choose Custom MX, add the row, then Save changes. Mail Settings is one choice for the whole of yourcompany.com: if it uses Namecheap Email Forwarding or Private Email today, Custom MX replaces their MX records, so add theirs as Custom MX rows too (Private Email: mx1.privateemail.com and mx2.privateemail.com, priority 10).
• Host Records appear when yourcompany.com uses Namecheap BasicDNS, PremiumDNS or FreeDNS. On Namecheap hosting nameservers, add the records in cPanel instead.
• Source: Namecheap’s help, checked 2026-09-27.

Amazon Route 53

• In the Route 53 console open Hosted zones → yourcompany.com → Create record, keep Simple routing, and finish with Create records.
• Add a TXT record: Record name _agentboxd.mail, Value the record’s value in double quotes. Repeat for each TXT record, with its own host part.
• Add an MX record: Record name mail, Value 10 mx.agentboxd.com.
• Route 53 wants TXT values in double quotes, and a value over 255 characters as several quoted strings on one line. The dashboard shows this provider’s values already quoted and split: paste them as they are.
• Source: Amazon Route 53’s help, checked 2026-09-27.

Squarespace Domains

• In the domains dashboard open yourcompany.com, then DNS → DNS Settings. Scroll to Custom Records and choose Add record (Squarespace asks for your password or two-factor code first).
• Add a TXT record: Name _agentboxd.mail, Text the record’s value. Repeat for each TXT record, with its own host part.
• Add an MX record: Name mail, Mail Server mx.agentboxd.com, Priority 10.
• Squarespace adds yourcompany.com to the name itself.
• Source: Squarespace Domains’s help, checked 2026-09-27.

Google Cloud DNS

• On the Cloud DNS zones page click yourcompany.com, then Add standard, and Create once the record set is filled in.
• Add a TXT record: DNS name _agentboxd.mail, record data the record’s value in double quotes. Repeat for each TXT record, with its own host part.
• Add an MX record: DNS name mail, Preference and mail server 10 mx.agentboxd.com..
• A TXT value over 255 characters has to be split into quoted strings of up to 255: the dashboard shows the DKIM value that way.
• Source: Google Cloud DNS’s help, checked 2026-09-27.

OVHcloud

• In the Control Panel open Web Cloud → Domain names → yourcompany.com, then the DNS zone tab and Add an entry. Pick the type, fill in the form and choose Add.
• Add a TXT record: Subdomain _agentboxd.mail, Value the record’s value. Repeat for each TXT record, with its own host part.
• Add an MX record: Subdomain mail, Target mx.agentboxd.com., Priority 10.
• End the MX target with a dot, as shown: without it OVHcloud appends yourcompany.com to it.
• Source: OVHcloud’s help, checked 2026-09-27.

Gandi

• Click Domain in the left menu, then yourcompany.com, the DNS Records tab and Add.
• Add a TXT record: name _agentboxd.mail, value the record’s value in double quotes. Repeat for each TXT record, with its own host part.
• Add an MX record: name mail, mail server mx.agentboxd.com., priority 10.
• Gandi requires the final dot on the mail server.
• A TXT string is limited to 255 characters, so the DKIM value goes in as several quoted strings: the dashboard shows it that way.
• Source: Gandi’s help, checked 2026-09-27.

IONOS

• Open Domains & SSL, click the gear icon under Actions next to yourcompany.com, choose DNS, then Add record and the type.
• Add a TXT record: Host name _agentboxd.mail, Value the record’s value. Repeat for each TXT record, with its own host part.
• Add an MX record: Host name mail, Points to mx.agentboxd.com, Priority 10.
• Changes can take up to an hour to show outside IONOS.
• Source: IONOS’s help, checked 2026-09-27.

Porkbun

• In Domain Management click DNS on the yourcompany.com row, fill in the form and click Add.
• Add a TXT record: Host _agentboxd.mail, Answer the record’s value. Repeat for each TXT record, with its own host part.
• Add an MX record: Host mail, Answer mx.agentboxd.com, Priority 10.
• Source: Porkbun’s help, checked 2026-09-27.

Hostinger

• In hPanel go to Domains, choose Manage next to yourcompany.com, then DNS / Nameservers → Manage DNS records.
• Add a TXT record: Name _agentboxd.mail, TXT value the record’s value. Repeat for each TXT record, with its own host part.
• Add an MX record: Name mail, Mail server mx.agentboxd.com, Priority 10.
• Source: Hostinger’s help, checked 2026-09-27.

Vercel

• In your team dashboard choose Domains in the sidebar and click yourcompany.com. Use the DNS record form on its Advanced Settings page and click Add.
• Add a TXT record: Name _agentboxd.mail, Value the record’s value. Repeat for each TXT record, with its own host part.
• Add an MX record: Name mail, Value mx.agentboxd.com, Priority 10.
• Source: Vercel’s help, checked 2026-09-27.

DigitalOcean

• Open Networking → Domains → yourcompany.com, choose Create a record, pick the type and click Create Record.
• Add a TXT record: Hostname _agentboxd.mail, TXT Value the record’s value. Repeat for each TXT record, with its own host part.
• Add an MX record: Hostname mail, Mail providers mail server mx.agentboxd.com, Priority 10.
• Source: DigitalOcean’s help, checked 2026-09-27.

Hetzner

• In the Hetzner Console choose DNS, select yourcompany.com, pick the record type and click Add.
• Add a TXT record: Name _agentboxd.mail, Value the record’s value in double quotes. Repeat for each TXT record, with its own host part.
• Add an MX record: Name mail, mail server mx.agentboxd.com. with priority 10 (or 10 mx.agentboxd.com. if the form has a single value field).
• TXT values have to be typed in double quotes, and one string holds at most 255 characters: the dashboard shows the values quoted and the DKIM key split.
• Hetzner adds yourcompany.com to a name or target unless it ends with a dot, so end the mail server with one.
• Zones from the former DNS Console (dns.hetzner.com) now live in the Hetzner Console.
• Source: Hetzner’s help, checked 2026-09-27.

Azure DNS

• In the Azure portal open DNS zones → yourcompany.com, choose + Record sets, then + Add, and Add on the Add record set page.
• Add a TXT record: Name _agentboxd.mail, Value the record’s value. Repeat for each TXT record, with its own host part.
• Add an MX record: Name mail, Mail exchange mx.agentboxd.com, Preference 10.
• Paste the DKIM key in one piece: the portal splits long values into 255-character strings itself.
• Source: Azure DNS’s help, checked 2026-09-27.

Any other provider

• Open the page where the zone’s DNS records are managed and add one record per row of the table above: type, name (or host) and value.
• If the form adds the zone to the name by itself, enter only the host part. If it asks for a fully qualified target and appends the zone to yours, end the mail server with a dot: mx.agentboxd.com.
• If the form rejects a value longer than 255 characters (the DKIM key), enter it as several quoted strings on one line: "first 255 characters" "the rest".

#Verification

A domain is verified once every required record checks out. Press Check now on its page (or call POST /v1/domains/:id/verify, at most once every 10 seconds per domain). We also check pending domains every 10 minutes for 7 days, and verified ones every 6 hours. DNS changes usually show up within minutes, sometimes a few hours.

Two webhook events follow the status, so you don’t have to poll: domain.verified when a domain passes its required records (the first time, or again after failed), and domain.failed when sending from it is paused. Both carry { domain, previous_status }.

#Rotating the DKIM key

Each domain signs with its own 2048-bit key on selector cm1. Rotate it once a year, or at once if you think it leaked. Mail keeps flowing the whole time:

• Press Rotate DKIM key on the domain’s page, or call POST /v1/domains/:id/dkim/rotate. You get a new key on the other selector (cm2, then cm1 again next time), listed as the dkim_next record. The current key keeps signing.
• Publish that TXT record next to the current one. Don’t remove the old one.
• As soon as a check sees the new record we switch signing to it: the background check runs every 10 minutes while a rotation is pending, and Check and switch now (POST /v1/domains/:id/dkim/activate) does it at once. A domain.dkim_rotated webhook fires.
• The old record is then listed as dkim_previous with a date 7 days out. Keep it until then, so mail signed just before the switch still verifies wherever it is delivered late; after that date it disappears from the list and you can delete it.

A domain’s dkim field shows the state: { selector, active_since, rotation_due, next, previous }. Once a key has signed for a year, rotation_due turns true, the dashboard shows a badge, and a domain.dkim_rotation_due webhook fires once. Rotating again while the old key is still being retired answers 409 dkim_rotation_too_soon; rotating while a rotation is pending replaces the pending key.

#Inboxes on your domain

Pass domain when creating an inbox. Reserved usernames (role names such as admin@, support@ and postmaster@) apply only on our domains: on your own verified domains you may use any name. Mail to addresses that have no inbox is refused during the SMTP conversation.

An address stays reserved once it has been used, even after its inbox or the domain is deleted. This also holds when the domain was used by another workspace before you: creating such an address answers 409 address_taken with “this address was used before and stays reserved”. Choose another username.

const inbox = await mr.inboxes.create({ username: 'ops', domain: 'mail.yourcompany.com' });
console.log(inbox.address); // ops@mail.yourcompany.com

#API

The SDKs have domains.create/list/get/zoneFile/verify/update/delete and domains.rotateDkim/activateDkim (zone_file, rotate_dkim and activate_dkim in Python). There is no MCP tool for domains: setting one up is a job for a person with access to DNS.