Just follow instructions and it goes as smoothly as it gets.
A gotcha for newbies like me:
Often the 'make' on sun is the Sun make, not the GNU make. Please make sure that GNU make is what gets called.
Also, nice to have gcc installed rather than sun's cc...
Also, if you are receiving errors such as:
Fatal error (11).make: *** [blessmail] Segmentation Fault (core dumped)
Try building with cc, by using --without-gcc