Gmail: Too many login attempts

Question

We have a .Net client to send emails through SMTP. We have our emails accounts over google apps technology (we use gmail with our domain). We have had problems with one email account because it can't send email. If we debug, we get this error: "Unable to read data from the transport connection: net_io_connectionclosed". All other email accounts are fine.

We tried using PHP with PHPMailer and we get this error:"Password command failed: 454 4.7.0 Too many login attempts, please try again later"

Curiously, the account can login using the Gmail web client (common Gmail interface). We checked the email password and configuration and there is no error apparently.

Thanks,

Answer 1

We had this issue and found that this was due to changed user behaviour which resulted our noreply@******.com account reaching its daily limits. On this link you can review G Suite reports on emails, and also please find the sending limits for SMTP, and for SMTP relay.

Answer 2

On the below page, make sure "Access for less secure apps" is set to Enabled. Sending SMTP through non-Google applications requires this.

https://www.google.com/settings/security

Also, make sure you have SSL enabled in your application.