Adding VMA Emailer as an SMTP relay for ssmtp is easy. Edit/etc/ssmtp/ssmtp.conf and add the following:

mailhub=smtp.elasticemail.com:587
AuthUser=elasticemailusername
AuthPass=elasticemailpassword
UseSTARTTLS=YES

Your changes will come into effect as soon as the next message is sent via ssmtp.