Can't reach key server - are you behind a (company) firewall?

If you can't reach any key server, chances are you are behind a firewall.

To work around this

1. open GPG Keychain
   
2. from the top menu select GPG Keychain > Preferences... (⌘ , Keyboard Shortcut)
   
3. Key server tab
   
4. paste hkps://hkps.pool.sks-keyservers.net:443 into the address field
   
5. press Enter to confirm

If that doesn't work, try the less secure hkp://hkps.pool.sks-keyservers.net:80 option.

If you are good friends with the IT department, ask them to open up port 11371 TCP and save your colleagues some trouble.