Example: a mail routing test matrix and a forwarding header before and after

What this example is

This is a synthetic worked example for the invented domain larkbakery.example. No real messages, addresses or providers are shown. It illustrates how a mail routing repair records its tests: who sent, who received, what happened and what the headers showed, before and after, so you can check each row yourself.

Before: outside mail arrives, website mail does not

The mailboxes moved to a new provider and the public MX records are correct. But the web host's routing setting for the domain was left on Local, so messages sent from the website to the company's own addresses stay on the host and never reach the new mailboxes.

• Outside senders follow public DNS and arrive.
• The website's own messages are handled by the host first.

If the matrix is wider than the box, scroll horizontally to read every column. Keyboard: focus the matrix and use Left/Right.

sender                     recipient               result       first receiving server in headers
outside provider A         sales@larkbakery.example   arrived      new provider
outside provider B         info@larkbakery.example    arrived      new provider
website contact form       sales@larkbakery.example   not arrived  web host (local mailbox)
host webmail (old)         info@larkbakery.example    not arrived  web host (local mailbox)

After: the route is the same for every sender

The routing setting is changed so the host hands mail for the domain to the new provider, and the host's local MX entries are made to match public DNS. The same tests are repeated and the receiving server is recorded again.

• Every row names the receiving provider, not the web host.
• Old local mailboxes are left untouched until you agree to close them.

If the matrix is wider than the box, scroll horizontally to read every column. Keyboard: focus the matrix and use Left/Right.

sender                     recipient               result    first receiving server in headers
outside provider A         sales@larkbakery.example   arrived   new provider
outside provider B         info@larkbakery.example    arrived   new provider
website contact form       sales@larkbakery.example   arrived   new provider
host webmail (old)         info@larkbakery.example    arrived   new provider

A forwarded message's verdict line, before and after

In a second synthetic case, info@ was forwarded to a personal mailbox at another provider. The lines below follow the format Microsoft documents for the Authentication-Results header. Before, the forwarded copy failed SPF, because the forwarding server is not allowed to send for the sender's domain, and its DKIM signature no longer verified, because the forwarding step changed the message, so DMARC failed and the sender's reject policy was applied. After, info@ is replaced by an alias in the same email account, which delivers the original message as the sender's own server sent it, so the signature still verifies. DMARC passes because at least one aligned check passes; here the DKIM domain matches the From domain.

• Before: spf=fail, dkim=fail, dmarc=fail.
• After: dkim=pass on the sender's own domain, so dmarc=pass.

If the matrix is wider than the box, scroll horizontally to read every column. Keyboard: focus the matrix and use Left/Right.

before (forwarded copy):  spf=fail smtp.mailfrom=bounces.sender.example; dkim=fail header.d=sender.example; dmarc=fail action=oreject header.from=sender.example
after  (alias delivery):  spf=pass smtp.mailfrom=bounces.sender.example; dkim=pass header.d=sender.example; dmarc=pass header.from=sender.example

What this example does not show

It does not show a guarantee of inbox placement, and the receiving provider's filters can still decide differently. It is an illustration of the evidence format, not a record of a delivery.