How can I configure Auto-Populating Instance email id in reply section

[sayaliwakch]

Hi Folks,

We're able to see the Email Option now in the ticket.

But we're not able to see the Email ID being auto-populated in the Reply to Field. 

Dev - AB CDE <devabctep@service-now.com>

QA - AB CDE <qaabctep@service-now.com>

Stage - AB CDE <stageabctep@service-now.com>

This email id need to auto-populate in reply to section as per instance.

Please suggest me how can I configure this functionality.

Regards,
Sayali Wakchaure.

[sayaliwakch]

In dev its working fine, Auto-populating email of dev instance but in QA instance it's not Auto-populating email 
Dev-