Is default email address in notmuch setup / lib useful?

[David Bremner <david@tethera.net>]

Currently notmuch tries to make a guess for a default email address
based on the "fully qualified hostname" of the host it is running
on. This is roughly equivalent to running "hostname -f". I have observed
two things

1) It's a bit flaky. There are various functions (gethostbyname,
getaddrinfo) that work in subtly different ways.  We've tried
three different setups in the test suite to test this, and none of them
work everywhere.

2) It doesn't seem that useful. The number of people running notmuch on
hosts that can (and want to) receive email seems pretty
small. Furthermore, it's not obvious we're going to get the right
name. For example on my laptop it returns "zancas.local", which is only
routable on my home LAN.

I could be wrong about 2, though.  If you actually find this to be a
useful feature, please reply to this thread.

If people agree it's generally not useful, I'd propose to replace it
with some simpler default like "localhost" [1], equally useful to for
testing, but simpler to implement and test.

[1]: required by at least RFC6761