Many providers (like Gmail and Yahoo ) now require OAuth2 or Two-Factor Authentication (2FA) . If you have 2FA enabled, your standard password will no longer work for IMAP; you must generate a unique App Password through your provider's security portal.
Repeated failed attempts can trigger a temporary IP block or account lockout from the provider's side to prevent brute-force attacks. 2. Structural Configuration Errors
IMAP requires three specific "keys" to open the door: the server address, the port number, and the encryption type.
Standard IMAP typically uses port 993 for secure SSL/TLS connections or port 143 for non-secure connections. Using the wrong port—or the wrong encryption method for a specific port—will result in a "Connection Refused" error.
