So, there are two different exceptions
Couldn't connect to host, port: smtp.gmail.com, 587; timeout 120000
This one means, that it could connect to gmail, but was not able to send an email within 2 minutes (which is a long time)
Caused by: javax.mail.AuthenticationFailedException: failed to connect, no password specified?
This one means that the user/password could not be successfully authenticated.
I have a hard time spotting the differences between the two setups, maybe you can explain this. Also make sure that after changing a keystore you either restart the node or reload secure settings. And make sure that setting is on every keystore on each node in the cluster (and reloaded), before trying further.