Is it possible to use the feature "copy" or "send to" for multiple documents? We can't work with "open in explorer", because we need the filter option in our library. Is there a code or tool for this "problem"?
I'm not sure this answers your question as I'm not sure if you're trying to download the files or copy them to a new library, but I'm assuming you're just after a bundle of files that can be mailed off. If that IS what you're after, I think I can help, if not, hopefully I'm at least getting you on the right track.
If you're running 2010, there are several solutions that enable downloading the files as a zip based on a selection in the web view. Here's an article on one such solution.
If you're running 2013 there's an easier option that doesn't require a farm install and uses the new app model. I gather you're NOT from your tags, but if someone else finds this later or you upgrade at some point, it might be useful.
Based on the OP's response, here are a couple more ideas that may help with your needs.
First option would be to use a PowerShell function to copy from one library to another. The code provided by the blog author will copy all files from a library, but it would not be challenging to add a filter to laser in on specific files based on properties. This would not be so helpful, however, if it's not easy to programmatically define what files should be moved.
Another option which is a little more klugey, but may work very well for your needs would be to add a checkbox column to your library called "Copy". From there, you can create a workflow that could be manually run and would ask the user what library to copy to. The workflow could then be configured to copy the file and clear the copy flag. Check this link for details.