Shoutbox

Without any kind of program running in the other user's computer, I don't think this is possible but someone will confirm this. If the other user is using Messenger Plus!, he can add you to his automatic accept request list by going to:
- plus options->instant messages->general options tab
- check "Automatically accept requests by default"
- choose the request type in the combobox
- click Filter contacts and select the users for automatic acceptance.

Upps, while writing this two people posted