Errors when syncing contacts from your iPhone to YouMail are rare but can happen. It can range from duplicate contacts being uploaded to no contacts appearing at all after giving the app permission to sync.
The latter can be due to a possible server error that our developers need to reach out to those who handle our YouMail server and repair.
If the issue is that duplicate contacts are being created, you can try to resolve it with the following steps:
1. Delete your YouMail contacts by going to YouMail.com, signing in, going to your contacts section, selecting all contacts and deleting them.
2. Re-upload your contacts by opening the YouMail app, tapping on the contact icon and tapping on the cloud icon on the top right