Salesforce Users Emailing Within Salesforce - 'From' Address Customer Sees Shows 'Salesforce' string! How can we remove and only show username?

When my Salesforce licensed users are emailing from within salesforce to customers - the email address the customer sees has the long string of random digits including 'Salesforce' in the string. Often times, customers have addresses like these going to their spam so our messaging isnt see.  

How can i revise this to work properly and only show the username / email from our sellers when they email out of salesforce and not this string of garbage? 

Thanks! 

Russell