What is the difference between Automatic InstantLinks and InstantLink Invitations?
You can choose to exchange InstantLinks with other sites that use LinkMachine by going to Add Sites to the List and selecting Exchange InstantLinks with other LinkMachine users. From there you can search by category or by entering keywords, and choose which sites you would like to exchange InstantLinks with.
Note that InstantLinks is a feature of LinkMachine Premium, so it is no longer available after a LinkMachine account's 10 day free trial of the Premium features has expired, unless the Premium or Premium SEO upgrade is purchased for that account.
After choosing some sites to exchange InstantLinks with, you will receive a message stating how many InstantLink invitations were sent, and how many InstantLinks were exchanged automatically. Those that were exchanged automatically are now completed link exchanges. For those that an invitation was sent, the link exchange will be completed when and if the recipient accepts the invitation.
What determines whether an invitation is sent, or the links are exchanged automatically? There are two factors. First, in order to be exchanged automatically, both your site and the site that you wish to exchange links with must have at least one category in common. That is, one of the three Site Categories that you selected under Site Settings must also have been selected by the owner of the site you would like to exchange links with. This is to prevent automatic exchanges between unrelated sites (irellevant link exchanges benefit no one).
Second, both your site and the site you would like to exchange links with must have an automatic InstantLinks "slot" free. The number of "slots" that a site has is determined by the setting Maximum Number of Automatic InstantLinks under Link Approval Settings. Some webmasters set this number to 0 to avoid allowing other sites to exchange InstantLinks with them automatically.
If both of those conditions are met, then the InstantLink would be exchanged automatically. Otherwise, an InstantLink invitation would be sent to the webmaster of the site you would like to exchange links with, and the link exchang will be completed once that invitation is accepted.