I configured my SCP with 2 Bussiness Unit: IT and MIS. In global setting I set incoming and outgoing mail  server with account support@domain.com

- In IT Business Unit I set incoming and outgoing mail with account: it@domain.com

- In MIS Business Unit I set incoming and outgoing mail with account: mis@domain.com

I fowarded mail from 2 account it & mis to account mail support@domain.com. When users sent mail to it@domain.com or mis@domain.com, SCP get them to request in related Business Unit but when I tried to reply it can't work, the system notice: " Sending notification failed". 

Note: when I set incoming & outgoing mail in any  Business same as in global setting ( support@domani.com), it can reply nomarlly

Thanks