zorem on "[Plugin: WP Mail SMTP] Plugin suddenly stopped working.."

I use this plugin on a few sites with gmail, suddenly since yesterday, the plugin does not work anymore, I did not do any change on the site and with the gmail passwords but when I try to send a test email, it say that there is authantication error.
Please advice, this is a crucial error, now I see that the plugin did not update for more then 2 years..

http://wordpress.org/plugins/wp-mail-smtp/