When you first try to access your Gmail account via Filtered from your server, it’s likely that Gmail will block access as a security precaution.
There are a few steps that you will need to go through to ensure that Gmail is configured properly to work with your Filter setup.
Enable IMAP in Gmail Settings
First, you’ll need to visit the settings page for your Gmail account and ensure that IMAP is enabled:
Authenticate Your Server with Google
Add your email account as described in Getting Started. In the Accounts menu, click the icon for List Remote Folders.
If you get a blank screen or an error, ensure that you’ve installed the php5-imap library on your server and restart Apache.
Then, check for a Suspicious Sign In email from Google:
Click on the link to troubleshooting client login:
If you’re using multiple gmail accounts, I recommend signing out of all of them. Then, sign in to just the gmail account you’re trying to activate with Filtered.
Once you’ve signed in, click on the Unlock Captcha link. Click the Continue button shown below.
Now, Filtered should be able to access your gmail account via imap.
Try clicking List Remote Folders again from the Accounts menu and you should see something like this: