No, unfortunately SMTP authentication in vCenter is not supported. You will have to disable authentication for vCenter on your SMTP server by whitelisting its IP address.
--- If you found my answers helpful please consider marking them as helpful or correct. VCIX-DCV, VCIX-NV, VCAP-CMA | vExpert '16, '17, '18 Blog: http://niktips.wordpress.com | Twitter: @nick_andreev_au