Dynamic groups in Sage CRM do not automatically get sent to MailChimp. If you send the group again you will create a new segment.

Within Sage CRM there is a scheduled job that retrieves the results of the campaign from the MailChimp server. This job is scheduled by default to run every hour.

If you are very impatient and want to know almost minute by minute whether people are reading your emails then you can also force a fetch of the data by clicking on the refresh button.

There is also an additional full synchronisation that runs every 24 hours that fetches data such as opt outs.

OK, thank you for your answer

It's ok for the synchronisation Results.

But for the synchro list SageCRM with Segment Mailchimp : i have several customers who use hundreds of list SageCRM to do small precise campaigns in Mailchimp : is there a way to not create a new segment when they send again the list and just refresh the MailChimp segment? If not, what is your advice ?

Thank you

This may not answer everything

community.sagecrm.com/.../sage-crm-and-best-practice-list-mananagment-in-mailchimp.aspx