When using the User Sync feature on a website with many different users (let’s say, over 1000), it can be much faster to synchronise them with your Mailchimp list using WP CLI.
Available CLI commands
The following CLI commands for User Sync are available. Before running any of these commands, ensure you have configured the plugin settings correctly.
wp mc4wp-user-sync all
Synchronises all users matching the criteria from the MC4WP > User Sync settings pages with the selected Mailchimp list.
Example: wp mc4wp-user-sync all
wp mc4wp-user-sync
Synchronises the user with the given ID with the selected Mailchimp list.
Example: wp mc4wp-user-sync 502
wp mc4wp-user-sync process-queue
Processes all pending jobs to synchronise local user changes with Mailchimp. It is advisable to setup a server cronjob that runs this command every few minutes as it will be more reliable then depending on the default WP Cron system.