Alpine is a text-based email client with support for IMAP, POP, and SMTP. It requires very little resources and works great on IRIX (again).
In 2021, Alpine is still under active development, but its initial release dates back to the early 2000s (its predecessor Pine dates back to 1992). But as with many older open-source software packages that were originally written to support a broad spectrum of UNIX systems, recent updates to the Alpine codebase neglected non-Linux build environments and broke compilation on IRIX.
Luckily, fixing things turned out to be pretty easy as Alpine already has
IRIX-specific #ifdefs and configuration macros in place which just needed a
few smaller fixes to get things to build again.
Alpine 2.24 source and binary packages are now available via the SGUG-RSE RPM repository. If you have set up SGUG-RSE, you can install Alpine on your SGI workstation like this:
sudo tdnf install alpine
Have fun!