GMail POP3 Authentication — Must Unlock Captcha

If captcha is enabled on your GMail account (and it is enabled by default), then GMail POP3 authentication will fail with this error (even though a correct login/password is provided)

**** Connected to
< +OK Gpop ready for requests from c23pf1097242ibu.22
< +OK send PASS
> PASS ****
< -ERR [AUTH] Username and password not accepted.

To successfully authenticate with from an email client such as Outlook, Thunderbird, or an application using Chilkat one must first unlock captcha:

  1. From the computer on which your signins are failing, visit
  2. Enter your Gmail username and password, and the letters in the distorted picture.
  3. Once you have successfully signed in, retry running your application using Chilkat.

Note: Unlocking captcha is not required to access a GMail account via the IMAP protocol (

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