Microsoft security workaround
Microsoft recently changed their security settings and it's gradually rolling out to Outlook users. The issue is that a connection cannot be made between Redtail and MSFT Outlook for broadcast emails. I've tried app passwords and every workaround suggested by Redtail and MSFT. In the end, MSFT said Redtail will need to develop something to work through the new security protocols. Until then, I have to send emails one at a time or impersonally through a bcc.