The support mailbox to which the requester sends an email would need to be added to Freshservice. Once this is done, email to ticket conversion can be set up in one of the two ways mentioned below.
Default Forwarding rule:
A forwarding rule would be set up at the support mailbox to forward emails to the Forwarded To address provided by Freshservice. Emails sent to your helpdesk would be automatically forwarded to this address and created as tickets on your portal.
Custom Mail Server:
In this instance, you would be using your own mail server for your support mailbox. Incoming emails would be fetched by Freshservice from the mailbox using IMAP connections and created as tickets on the portal.