When inserting custom content in communication templates (LionDesk content, ie. customer name, {{firstname}}, etc.), do not send {{firstname}} if the customer's first_name field is blank. And similarly across other blank LionDesk custom content fields.
Alternatively, we could replace {{firstname}} with "there" in case of use in the salutation; however, this does not work effectively using "there" in place of {{firstname}} elsewhere in an email or text.