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 email to NOT be seen once it has been downloaded by a POP3 or IMAP client. You’ll need to change your GMail account setting for “Forwarding and POP/IMAP” access. The option to choose is this:
When messages are accessed with POP: Keep GMail’s copy in the Inbox
See the screenshot below: