How to remove desk-mailer.zohodesk.eu from New Ticket email from address

Can someone advise how to remove the desk-mailer.zohodesk.eu From the auto email.

Both the Agent and Customer email as this email address in the from and it looks very ugly and unprofessional.

I have setup the additional email accounts and custom SMTP settings and these appear to work.

I also went and edited the Email Template

"Acknowledge contact on receiving a new ticket"

"Notify all agents when a new ticket is created"

in the From field and selected the custom email address. But it is still coming through with this

help.desk=DOMAINAME.co.uk@desk-mailer.zohodesk.eu; on behalf of; Help Desk <help.desk@DOMAINAME.co.uk>

replaced actual DOMAINAME with DOMAINAME to avoid spam

Please can someone advise

Thanks