D in delete messages

For GOD SAKE, tell me how to make the messages desappear when they are deleted 
and not show that #$@#$ D. I can't take anymore users complaining about 
deleted messages only desappear when they go out and back to inbox or other 
directory. And while they don't see the message desappear they don't believe 
it was deleted.

Any help would be more than welcome.

Thanks a lot for your attention.

flavio fonseca