Comment 7 for bug 989838

I believe the issue does have to do with proxies.

I have the same settings as Ian in system.proxy (also couldn't find org.gnome.system.proxy), except that in https proxy, I had host set to localhost. Under both http and https settings, I clicked on localhost and pressed the 'set to default' button. Doing so appears to resolve the issue and gmailwatcher works.

However, this still appears to be a bug of some sort, because in my network settings, the proxy server is disabled. It seems that gmailwatcher is using the proxy hostname settings even though the proxy server is disabled. It would be nice if there was a way to have non-default proxy settings, and also use gmailwatcher.