Sup 0.20 introduces the possibility to open the uri that is under the cursor with the g key as described in Follow an uri.

Being not very supportive for mice Sup does not implement clicking on links within an email, but many terminals can be configured for link clicking

Configure URxvt to match links and open in web browser on right-click by adding the following to $HOME/.Xresources

URxvt.perl-xt-common: default,matcher
URxvt.urlLauncher: iceweasel
URxvt.matcher.button: 3
URxvt.matcher.pattern: \\bwww\\.[\\w-]\\.[\\w./?&@#-][\\w/-]

where iceweasel is your browser command.

urxvt-perls includes an extension that lets you select urls with the keyboard.