linking breaks with lack of log10l

[dancorl]

I tried to compile hypermail 2.4.0 with make, as in INSTALL, at it broke at linking because it could not find some math functions. It happens when linking hypermail and lang. It worked after I reentered the link command(s) and appended '-lm' after each. Please correct the makefile.

[dancorl]

I ran it on a 185000 messages mailbox, it performed well until it crashed and dumped core while generating authors.html.