Got an email from a client who states, "when I click on the link from the email to "accept" the portal for uploading documents, it states "email is not found."

This happens every year with this client.  I want to get to the bottom of it.  I thought we were able to unsend a link now, but I don't see that option.  I would like to change the email address to another one she has and try that.  Any advice as to how I can work with this client on fixing this issue?