How to synchronize my users e-mail addresses?

First of all, make sure you have chosen a Mailchimp list in which to synchronize all your e-mail addresses.

The purpose of user synchronization is:

• to export all the e-mail addresses of people who have subscribed to your newsletter through the PrestaShop native module but who are not yet customers. To do this, you must define the language that will be assigned to them as explained here.
• to export all your customers' e-mail addresses. To do this, you must decide whether you want to subscribe them by default to your newsletter or respect their choice as explained here. If you decide to respect the choice of your customers (recommended), the e-mail addresses of customers who have not subscribed to the newsletter will still be exported but will only be able to receive transactional e-mails, not newsletters (promotional e-mails).
• to start the real-time synchronization of any new subscriber to your newsletter

Note: of course, if you have defined exclusion rules for e-mail addresses, the concerned e-mail addresses will not be exported to Mailchimp.

Once you have made the configurations mentioned above, go to the "Manual Synching" section of the "Users list synching" tab. When this first synchronization has been performed, the automatic synchronization of any new subscriber will be triggered. Of course, you will always have the possibility to manually synchronize your users again, if necessary.

Click on "Export users".

A window opens reminding you first of the list to which the e-mail addresses will be exported:

In "Preferences for users e-mail addresses synchronisation", the module displays the total number of e-mail addresses that will be exported:

If the number of email addresses is really very large, or if the performance of your server does not allow synchronization of too much data at once, then you have the ability to set the number of e-mail addresses to be sent "per batch". Indeed, synchronization is done by successive sendings of data batches, each batch containing a certain number of items (here e-mail addresses). Decrease the number of e-mail addresses per batch if the synchronization returns errors.

Click on "Synchronize".

During synchronization, you can track the progress of data processing in a visualization window. This way, for example, you can see which batches of data have already been processed and which are currently being processed. The window will automatically close once the synchronization is complete. If you accidentally close the window by clicking outside for example, simply click on the "Export Users" button again to open it again and continue following the process.

Once the synchronization is complete, check on Mailchimp that you have all your contacts.

Any new subscriber to your newsletter will then be automatically synchronized. If for any reason you need to restart your users' manual synchronization, repeat the same steps as before.

Know that the module contains a dashboard that allows you to check the status of synchronizations, and whether or not there have been any errors. To do this, go to the "Sync status" tab in the module "General settings" section, select a period (in days) to be analyzed and click on "Search". The module will then display the synchronizations that have been made during this period and any errors generated.
In the "Diagnostic tool" subtab you can search for the synchronization status of a particular e-mail address and re-synchronize it if necessary if there has been a problem during manual or automatic synchronization.