The signer didn't receive email notification from Docusign

@Tsugumi

Sorry to hear that you experience issues with your signers not receiving the Docusign email notifications. If they have a Docusign account they can simply login to get access to the documents and sign them regardless of the email notification.

In Docusign eSignature users is able to configure which email notifications they want to receive. Therefore, one reason is that they may have opted out. More likely the email got blocked internally, which is why reaching out to their IT department is most promising.

This Docusign support article has additional information on the topic that may help to resolve this.