Ssmtp which used to work for me, WR RC3, now sigsegvs, though the package hasn't changed.
Ergo, something else has broken it, my guess is libpthread?
last few lines of strace
<snip>
open("/etc/ssmtp/revaliases", O_RDONLY) = -1 ENOENT (No such file or directory)
read(0, "blah\n", 4096) = 5
read(0, "", 4096) = 0
rt_sigaction(SIGALRM, {0x10000000, [], SA_SIGINFO|0x404654}, {SIG_DFL}, 16) = 0
alarm(600) = 0
--- SIGSEGV (Segmentation fault) @ 0 (0) ---
+++ killed by SIGSEGV +++