I have installed contact module and SMTP Authentication Support but do not appear in Structure tab I have Drupal 7.22 installed, I have installed some modules, but there are two modules that appear correctly installed but I cannot see their configuration in structure. 
These modules are Contact and SMTP Authentication Support.

Previously I had some issue with the cache in Configuration tab, and I empty the cache, and it worked, but in the Structure tab even if I do it, I don't solve it.
You should install the devel module from http://drupal.org/project/devel and after that you can select rebuild menu or flush all cache function. (From the devel menu)
If i doesn't work, maybe there was some problems with your installation. You should disable and enable these modules again or run update.php script.