Custom domains

A custom domain lets permanent addresses use your own domain, for example signup@mail.acme.com. Once verified, only your organization can create addresses on it.

Every domain receives test mail. Sending as the domain is an option you turn on per domain:

• Receive test mail (always on): Mailwurf receives all mail of the domain. Use a dedicated subdomain such as mail.acme.com or test-mail.acme.com, never a domain that already receives real mail.
• Send as this domain (optional): inboxes on the domain can send, for example signup@mail.acme.com. Turning it on adds the records for sending.
• This domain already has a mail server (optional, with sending): for your main domain, for example billing@acme.com on receipts. acme.com keeps its mailboxes; see A domain with its own mail server.

Temporary inboxes always use the Mailwurf mail domain.

Add a domain

Owners and admins can add domains.

1. Open Domains.
2. Under Add custom domain, enter the domain, for example mail.acme.com. Enter only the domain, without https://.
3. Select Add domain.

The domain appears under Organization domains as pending, with the DNS records to publish. To send as your main domain, add acme.com the same way, then turn on sending with its own mail server before you publish any records.

Publish the DNS records

Create these records at your DNS provider. The dashboard shows the exact values for your domain, each with a copy button. The For column says which option each record belongs to.

Many DNS providers ask for the MX priority in a separate field. Enter 10 there and mail.mailwurf.io as the mail server.

Verify

After the TXT record is published, select Verify DNS. The domain turns verified.

If verification fails with TXT record _mailwurf is missing or does not match., check the record name and value, and wait for DNS to update before trying again.

Verification only checks the TXT record. Mail only flows once the MX record is in place.

Turn on sending

Turn on Send as this domain on the domain card. Three records are added to the list:

Mail you send is only accepted reliably once these are published. While sending is off, inboxes on the domain still receive, but sending from them fails with Sending is off for mail.acme.com. Turn it on in the domain settings. Turning sending off again does not change any address.

A domain with its own mail server

Your main domain, acme.com, already receives mail at Google, Microsoft or another provider. Mailwurf must not take its MX record. Turn on Send as this domain, then This domain already has a mail server. Mailwurf then uses send.acme.com for bounces and replies; you only see it in the DNS records.

None of these touch the MX or SPF record of acme.com. The card shows whether acme.com already has a DMARC record; keep an existing one.

A permanent address billing on the domain sends as billing@acme.com. It receives at billing@send.acme.com, so replies arrive in the inbox. Mail to billing@acme.com still goes to your own mail server, so use a subdomain without real mail for addresses your tests send mail to.

The option changes where the domain's addresses receive. It can only be switched while no address uses the domain; otherwise you see Remove inboxes and forwarding rules on this domain before changing where it receives mail. Turning sending off also turns this option off.

While acme.com uses its own mail server, send.acme.com cannot be added as a separate domain, and the other way round.

Forward mail

Mail for an address without inbox can go on to an address of your own, as with Cloudflare Email Routing: support@mail.acme.com arrives in your Gmail. Forwarding works on domains whose mail arrives at Mailwurf, not on domains with their own mail server.

Add a forwarding address

1. Under Forwarding addresses, enter the address mail should go to and select Send confirmation.
2. Open the mail Mailwurf sends to that address and select Confirm forwarding.

The address shows confirmed. Until then nothing is forwarded to it. Send again mails a new link (once a minute); a link works for seven days.

Add a rule

On the domain card, under Forward mail:

1. Enter the part before the @, for example support, or tick All other addresses.
2. Pick a confirmed address, or Drop the mail to accept it and throw it away.
3. Select Add rule.

Inboxes always keep their mail: a rule cannot use the address of an inbox, and All other addresses only covers addresses without inbox or rule. Addresses without inbox and without rule are still refused.

What gets forwarded

• The mail arrives unchanged, with its original sender, so replies go to the sender.
• Mail that fails the sender domain's own checks (DMARC, or without DMARC neither SPF nor a valid signature) is not forwarded and is refused.
• Forwarded mail counts toward the organization's sends per minute.
• Mailwurf does not keep forwarded mail.

Rules go when you delete the domain. A forwarding address can only be removed when no rule uses it.

Use the domain

Register a permanent address and pick the domain next to the name. Addresses on custom domains do not count toward the five permanent addresses on the Mailwurf mail domain.

Delete a domain

1. Select the trash icon next to the domain.
2. Confirm with Delete domain.

A domain can only be deleted when no address uses it. Delete its addresses first.

Rules