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Some forwarded email has no Mailyoto DKIM signature

Why only some forwarded messages carry a Mailyoto DKIM signature, what the ARC seal does, and how DMARC is affected.

Updated 27 October 2026

You open the headers of 2 forwarded emails. One has a DKIM-Signature with d=yotosend.com, and the other has none.

Why it happens#

Mailyoto adds its own DKIM signature, with d=yotosend.com, to about 70% of forwarded messages. It always signs a message when it rewrote the From line, as it does for some replies from your alias. Mailyoto forwards the rest without its signature, on purpose, while the signature builds up its reputation with mailbox providers.

Every forwarded message gets an ARC seal from Mailyoto, also with d=yotosend.com. The seal records the authentication results Mailyoto saw when the message arrived. Your inbox provider can use them after forwarding.

What it changes for DMARC#

DMARC checks the sender’s domain, the one in the From address. A d=yotosend.com signature never matches that domain. It doesn’t make DMARC pass or fail.

What decides DMARC on a forwarded message is the sender’s own DKIM signature. Mailyoto leaves it in place, and your inbox provider checks it. When it says dkim=none, the sender didn’t sign the message at all.

Email you send through Mailyoto is different: Mailyoto always signs it with your own domain. See Setting up DKIM.

What to do#

  1. Leave your settings as they are#

    There is no setting for the forwarding signature. Its absence on a message is expected.

  2. Check the sender’s signature#

    Open the message’s full headers and find the Authentication-Results line from your inbox provider. Read message headers shows where it is. dkim=pass for the sender’s domain is what matters.

  3. Ask the sender to sign their email#

    If it shows dkim=none or dkim=fail for the sender’s domain, the sender sets up DKIM with their email provider.

Confirm it worked#

The next message from that sender shows dkim=pass for their domain in its headers.

Unsigned forwards land in spam

The Mailyoto signature doesn’t decide DMARC. The sender’s own signature and reputation matter most. Forwarded email goes to the Spam folder lists what to check.