How can I add an email address to which my customers can write and create tickets on Freshservice?

You have started with freshservice and would like to add an email address to the portal so that when customers write to this address, all the emails would be converted into tickets. 

In order to process this, please navigate to Admin --> Support Channels --> Email --> New service desk Email and add this email address here. Once this is done, a "Forwarded To" address is generated which has to be set up in your mailbox.Kindly refer to the below solution article for more information on the same: https://support.freshservice.com/support/solutions/articles/154123-setting-up-your-support-email-address