Hello

I have Exchange server 2013 CU1, the problem is in smtp when i have the same user in domain and subdomain. Example:

i have admin@domain.com, and also have admin@sub.domain.com

admin@domain.com can send emails normaly, but admin@sub.domain.com can not send emails and receiver this error:

550 5.7.1 Client does not have permissions to send as this sender

the resolution is to open 'admin@sub.domain.com'  properties and the go to mailbox delegate ans set send as permission with 'admin@domain.com'

the problem just with domain and subdomain but not with two different domains

I need resolution for this issue without set send as permission 

thanks.