Mail sent from Gmail sometimes fail with error "535 Authentication Failed"

Mail sent from Gmail sometimes fail with error "535 Authentication Failed"

Hi!

I have been using email sending from Gmail via SMTP for a few years now, and have never had any problems, until a few days ago, when after sending the message I was notified by mailer-daemon@googlemail.com that the message had not been sent because authentication had failed (535 Authentication Failed).

I thought maybe the password had simply expired, so I generated a new one and did the configuration again in Gmail. For a few days it worked without a problem, but today I got the same error message again. I then later tried to send other emails, and was able to send them without any problems.

So the password is correct and it works, but there seem to be only sporadic temporary authentication problems.

Are you aware of this? Do you know how I could solve it, or is it something you have to fix?

Thank you