Change default checkbox from unchecked to checked on massremove page:
admin/massremove.php
Change this line:
<input type="checkbox" name="blacklist" value="1">
To:
<input type="checkbox" name="blacklist" value="1" checked>
Change default checkbox from unchecked to checked on massremove page:
admin/massremove.php
Change this line:
<input type="checkbox" name="blacklist" value="1">
To:
<input type="checkbox" name="blacklist" value="1" checked>