@mulander In this case the port required the use of STARTTLS, which I think isn't supported by nc(1), but otherwise #OpenBSD's netcat is an awesome tool for this purpose.
Come to think of it, it would probably be nice to have something like the '-s' option in gnutls-cli for this purpose.

@karasu @mulander
btw. isn't socat an even more awesome tool?

@Wolf480pl socat is for sure nice and has some extremely useful features, but - at least for me - netcat is sufficient most of the time and doesn't require any manpage lookups. ;-)
Both netcat and libre/openssl are installed as part of the default images of most systems. Finding socat preinstalled is pretty rare in comparison.

@karasu dunno, I only remember netcat's -l option, and often need man to tell if it's `-p port` or just `port` (gnu vs bsd netcat).

Also, on most (GNU+)Linux distros I use, there's no concept of "base system" or "preinstalled software". And even if there is a similar concept, it usually doesn't contain netcat (or even dig).