CERT_NONE + gmail = no certificate received?

[Ethan Schoonover]

I'd also suggest confirmation that the sslcacertfile path is present
in your config, and on top of that suggest that you confirm that it's
a valid cacert file at all. Specifying a sslcacertfile in the
offlineimap configuration file doesn't yet change the error (i.e. will
still throw a "no cert received error") if the setting is there but
pointing to the wrong file / no file.

Ethan Schoonover
es at ethanschoonover.com
http://ethanschoonover.com