I've been receiving e-mails with the subject "InstantLink Exchange" or "InstantLink Invitation". What do these mean?

Each InstantLink Exchange e-mail notifies you of a link exchange between your site and another site that uses LinkMachine. This exchange was initiated by the webmaster of the other site, and there is no need for you to do anything else. If you would like to remove an InstantLink exchange from your link directory, you can log into LinkMachine, set "Show" to "InstantLink Exchanges" and click "Remove" for the one you'd like to remove.

The InstantLink Invitation e-mails notify you about a site that has requested a link exchange with your site. To accept one of these link exchange invitations, log in to LinkMachine, set "Show" to "Invitations Received" and click on "Accept" for those those you wish to accept. You can also click on "Decline" for any you would rather not exchange links with.

If you would like to manually approve all InstantLink invitations, rather than allowing any links to be exchanged automatically, you can do so as described here.

Also, if you'd like you can filter out unwanted InstantLink submissions automatically by specifying words used in the title or URL of the submitted sites, or by the e-mail address of the webmaster sending them out, as described here.