threading and timeouts

[Piers Lauder]

Are timeouts possible inside threads?

Eg: escaping from an attempt to use smtplib.SMTP().sendmail() inside a
child thread if the remote host is being extremely slow.

It doesn't seem possible to use the traditional signal(SIG_ALRM,...)
approach because signals only work inside the main thread.

The only option I can think of is to re-write the smtplib module to use
`select', but does anyone know of a simpler solution?