Dear all

I want to migrate users from exchange 2010 to zimbra.
I start zimbra migration wizard and query the users1~user100.
I select 100 users and press next, it returned error message every 30 users. It said:

Error accessing account user31@exmaple8.com. The remote server returned an error503) Server Unavailable.
Error accessing account user62@exmaple8.com. The remote server returned an error503) Server Unavailable.
Error accessing account user93@exmaple8.com. The remote server returned an error503) Server Unavailable.

How do I resolve this error?

1.gif
2.gif
3.gif