Is it possible to extend Tcl in Quartus by adding outside packages? Specifically, I am looking to autosend emails and/or SMS messages based on Quartus compilation status.
Yes, you can add outside packages. There are a number of packages that ship by default – there is a set of packages called “tcllib” that you can look up the documentation for. If the packages there don’t cover what you need, you can find a package to download, and copy the files to a known location. Then in the Tcl script, you configure the script to look in that location.
Quartus does have the ability to send compilation notifications, but you need an Intel account. Check the settings in the Tools menu -> Options -> Internet Connectivity -> Notification.