SMTP Error: Could not authenticate.

[eluser]bientek[/eluser]
PHPmailer suddenly stopped working for me too. My CI app also relies on PHPmailer, and suddenly cannot authenticate either (after a year of it successfully working with smtp.google.com, TLS port 587). I suspect that it may be due to a change on the server that my hosting company had just made. (I suspect this because I had just asked several hours earlier for them to check the spam logs for any indication of spam being sent from my server, and since their reply that they had "sent a test email", it now consistently produces this error.)