4.10 Where is pine?

Due to its restrictive license, it's in the non-free area. Moreover, since license does not even allow modified binaries to be distributed, you have to compile it yourself from the source and the Debian patches.

The source package name is pine. You can use the pine-tracker package to be notified about when you need to upgrade.

Note that there are many replacements for both pine and pico, such as mutt and nano, that are located in the main section.