If you see something like this when installing MIME::Tools:

t/Smtpsend.t ......... accept failed: Connection timed out at t/Smtpsend.t line 46.

# Looks like your test exited with 110 before it could output anything.

t/Smtpsend.t ......... Dubious, test returned 110 (wstat 28160, 0x6e00)

Then, I bet you have a dual-core or dual-processor system!

Easy enough to fix, using your editor, edit t/Smtpsend.t at line 46:

vi +46 t/Smtpsend.t

Add a line so that the section looks like this:

sleep 1;

# In the parent
my $s = $sock->accept();
if (!$s) {
    kill(9, $pid);
    die("accept failed: $!");
}

Then, make test, and make install.  The problem is the $sock->accept() gets called before the connection.