How to let a user know his inbox is full?

Hi everyone. Not sure if this is the correct section if not Im sorry.

I wanted to know if its possible to let a member on here know that their inbox is full. I was speaking to a member on here and he was giving me some decent advice and Im not able to reply now as his inbox is full. Now I look like I have just taken all the advice and not replied or said thanks.

he will be informed by BHW, when he trying to send PM for another one, error message will appear so wait till he clean it,

i believe you can leave a visitor message or check if he/she specified any other methods to reach him/her (skype, yahoo, icq etc)

He will know his PM's are full, so It's up to them now. As above, leave a visitor message maybe?