Also, to prevent these scams from occurring, ALWAYS <span style="font-weight: bold"><span style="color: yellow">Copy and Paste</span></span> the AIM address in the user's signature and ALWAYS <span style="font-weight: bold"><span style="color: blue">have them post in your thread OR PM you!</span></span>
The only way to prevent a scam like this is to verify the identity of the person you are talking to.
If they say that they cannot post at that time or cannot log in; simply tell them that they can contact you later, after they are able to do so.