Different contacts number in Zoho CRM view and Zoho campaigns mailing list that are synced

Different contacts number in Zoho CRM view and Zoho campaigns mailing list that are synced

Hello, 

as already mentioned in the title my problem the difference between contacts number in Zoho CRM view and Zoho campaigns mailing list that are synced. 

The problem concerns the following:  Zoho CRM view 'All Europe' contains  58114 contacts whereas the  mailing list that is based on the sync with the same title contains only 29663 contacts. Even taking unsubscribers (1068) and b ounces  (7122) doesn't help finding the reason of this difference. The sync is in weekly mode and was done after adding new contacts so that sloudn't be an issue.

I would be grateful for your help.

Best regards, 
Anna