[user02934123123]

Since Lynne's already answered one of your two questions, I'll take a stab at the other:

Originally Posted by queengoc

1. I don't want Save a copy of this message in your Sent Items folder. to no longer be automatically checked. The inboxes get full quite fast due to this being automatically marked.

To do this, go to AdminCP > Style Manager > Your Style > Edit Templates. From the list of templates, double click on Private Message Templates, then open the pm_newpm template in the editor.

Find the following line, and particularly the bit in red:

<div><label for="cb_savecopy"><input type="checkbox" name="savecopy" value="1" id="cb_savecopy" tabindex="1" $checked[savecopy] /><phrase 1="private.php?$session[sessionurl]folderid=-1">$vbphrase[save_copy_in_sent_items_folder]</phrase></label></div>

Change the red bit so it reads:

<div><label for="cb_savecopy"><input type="checkbox" name="savecopy" value="0" id="cb_savecopy" tabindex="1" $checked[savecopy] /><phrase 1="private.php?$session[sessionurl]folderid=-1">$vbphrase[save_copy_in_sent_items_folder]</phrase></label></div>

That ought to do it.