GMail IMAP NO [AUTHENTICATIONFAILED] Invalid credentials (Failure)

You passed the correct login/password to login to, but you still get an “Invalid credentials” error.  What gives? For example, you called Chilkat’s Imap.Login method, passing the correct login/password, and the imap.LastErrorText contains this: authenticateLogin(110ms): loginImap(110ms): ConnectionType: SSL/TLS ImapCmdSent: aaab LOGIN “” getCompleteResponse(110ms): ImapCmdResp: aaab NO [AUTHENTICATIONFAILED] Invalid credentials (Failure) –getCompleteResponse –loginImap isOK: serverResponse: aaab NO [AUTHENTICATIONFAILED] Invalid credentials […]

GMail IMAP OAuth2 – A Walkthrough

This blog post covers from start to finish the process for getting a desktop application working with GMail using the IMAP protocol with OAuth2 authentication. Start here: (1) The first step is to create credentials.  Your app is a desktop application.  HOWEVER, you will be creating credentials as if your app is a web app. See this YouTube video […]

GMail “Allow Access for Less Secured Apps”

Question: I created a Gmail account and I am SendEmailAsync to send email via that Gmail account through a VB6 program. I had to turn on “allow access for less secured apps” for that Gmail account but otherwise, I am able to get everything working. However, after some weeks of inactivity, Google would automatically turn disable access for less secured […]


Question: I am trying to send email via GMail using the SMTP protocol.  I am sending the correct GMail login credentials, but I get this error: … smtpAuthenticate: login_method: LOGIN auth_login: smtpSendGet2: sendCmdToSmtp: SmtpCmdSent: AUTH LOGIN –sendCmdToSmtp readSmtpResponse: SmtpCmdResp: 334 VXNlcm5hbWU6 –readSmtpResponse –smtpSendGet2 sendCmdToSmtp: SmtpCmdSent: *** –sendCmdToSmtp readSmtpResponse: SmtpCmdResp: 334 UGFzc3dvcmQ6 –readSmtpResponse sendCmdToSmtp: SmtpCmdSent: {PasswordOrCredentials} –sendCmdToSmtp readSmtpResponse: SmtpCmdResp: 534-5.7.14 < […]

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 > USER < +OK send PASS > PASS **** < -ERR [AUTH] Username and password not […]

GMail Labels are just IMAP Mailboxes

Question: I’m going to be using them in VB.Net to process a GMail inbox. In GMail they use Labels instead of folders. Are the labels that belong to an email visible via your tool? Ideally the VB application would process the inbox, and perform actions based on the label. Answer: I investigated and it refreshed my memory. GMail “labels” are […]

Deleting email in GMail

(A tip from a Chilkat customer.) The only way to delete emails on Gmail is in three steps: 1. Copy the email(s) to the folder called [Gmail]/Trash 2. Select all of the emails in [Gmail]/Trash and set the Deleted flag 3. Execute ExpungeAndClose or Expunge command I found that this is the only way to truly delete emails from Gmail.

Understanding GMail’s Behavior

This blog post will explain GMail in a way that will help you understand it’s seemingly strange behavior. The question that prompted this post is as follows: I am able to read mails from GMail mailbox using MailMan object. Is there any options to delete a mail permanently from GMail mailbox? When I am using the DeleteMail method the mail […]

GMail Settings for POP3 and IMAP Access

The most common problem with reading email from GMail using Chilkat’s POP3 and IMAP API’s is the following: The user can see certain emails when interactively logged onto GMail with a web browser, but cannot see those emails using Chilkat’s POP3 or IMAP component. The problem is caused by a setting in your GMail account. The default setting causes an […]