When you are ready to send an invoice to your customer(s), select the email option and enter your contact’s e-invoicing email address. This is a unique @invoi.ci address that contains your organisation’s UEN, eg. 0195-SGUEN12345678D@invoi.ci where 12345678D is the UEN. Tip: Add your contact’s e-invoicing email address to the contact record in Xero. If an email already exists, select Add another person and enter the email as a secondary address and check the box Include in emails.