How can I realize a module that can send and receive e-mail invitations, e.g.:

1. User does a specific action
2. An e-mail is sent to his e-mail adress with a link inside like http://mysite/register.aspx?uid=234&action=24
3. When the user clicks the link inside the mail the page is executing some action

The main issue I face is that I do not know how to generate a robust link, because I do not know before on which tab (and how often) the module is placed (actually the link we send is not for an e-mail verification, but to notice a person in our office the an employee has made a request which has to be approved or not by clicking that link in the e-mail so the workflow can continue to the next supervisor or back to the employee).

Thanks Erik, I thought about using that way too. Anyways I am worried what will happen if the module might be moved from one Tab to another, while there still could be active emails in some of our users mailboxes, so they would click the link and go nowhere while the actual workflow breaks (we have some approval stages and usually one workflow can be some days until finished).

Isn't there a possibility to do something with a more or less fixed page like www.mydnn.com/default.aspx?param=value&... so that every module instance will used that fixed entry point?