SIOG1528 | Introduction and organisation: communication: communicating by external email: changing your Outlook settings

Before you email a customer you should consider disabling Outlook Auto Complete (File > Options > Mail > ‘Send Messages’ section > Uncheck ‘Use Auto-Complete list to suggest names when typing in the To, CC and BCC lines’)

If you use Contact Lists in Outlook, you may wish to create a separate External Contacts List to save addresses for any customers who consent to use email with you, which should help prevent you mixing up the customer contacts with HMRC Global Address List or other Internal Contacts.