So, my SMTP plugin on wordpress works when I use my user email address to send emails. But when I try to keep the username, user@domainname.com that works by itself and change the "send from" to the Group email alias, it says it can not authenticate with the SMTP server.

The fields I have to enter are:

From Email: which works if the from email is the same as the SMTP username. So, user@domainname.com

I generated an Application specific password which works with making the From Email and SMTP username the same, but if I change the From email to group@domainname.com and keep the SMTP username the same as the previous one. I get an authentication error.

I followed this based on this other Post: https://help.zoho.com/portal/en/community/topic/using-smtp-to-send-email-from-a-group-email-address