I have a new server now and trying to copy old costumers to my new server one by one.

But I noticed that

if the account that i copied from my ex server, has the existing email accounts, these mail accounts working fine.
But after copying to new server, if i add a new email account, that email address not working both in webmail and outlook.

I checked different accounts and many times. New email accounts doesnt working. Not sending and not recieving.

PS: But new email accounts which are created in new (present) server can send and recieve emails between them. ( if both sending account and recieving account are on the new (present) server)
But these accounts dont send/recive any email address to another server


Do you have any idea?