When migrating from 1&1 hosted Exchange, you should specify the following:
- For the connector, specify a URL of https://exchange.1and1.com/owa as shown below:
- For each mailbox, specify the email address and 1&1 user name as shown below:
To find the 1&1 user name associated with each mailbox, you can:
- Log in to the 1&1 admin console
- Log in to OWA and navigate to Options -> About -> Exchange mailbox address.