PEAR and PHP 4.0.6

Hello to all, I don't have a lot of experience with pear-packages. I just played around with pear-db on php 4.3.10. Now I plan to use some packages (db, mail, text, file system and perhaps others) for a new project. But the PHP-version I have to use is 4.0.6. PHP 4.0.6 is released 23 June 2001, the initial releases of most of the pear packages seem to be dated from 2002. I saw that db and file depend on 4.2 or newer. For mail I don't find similar information. My question is: Is it possible to use some packages with 4.0.6? And if so: Is it too risky? Unstable? Should I have a closer look or forget it at once? It would be nice if some people with more pear-experience can give me a hint. Thank you Sabine