I have several live sites on a single install. Just realised emails are not being sent out for some reason and customers are complaining. 

Email is not sent out for reset password feature. I also tested registering new users, the confirmation emails are not sent out. 

I tested the SMTP settings. The test email is sent successfully and I  receive a SMTP Configuration Test email. 

I checked admin settings. The Admin tab is linking to an admin user, the admin user has the email address that emails are sent from. So should be fine too. 

The domain was made into SSL along with email server a couple of months back. The SMTP email setting is currently set without a tick in SSL. Sending port 587. With the tick it fails. Without the tick it succeeds. 

There is also another portal on the same install. This domain is also not sending email out, even though the email and domain address is different. 

My biggest confusion with DNN is that it has only one place to set SMPT irrespective of multiple domains. How does this work? So confusing. Shouldn't there be a separate SMTP setting for each portal? And the SMTP sending succeeds, then why no email is sent out. 

I also checked Messaging Dispatch in Schedule. It is succeeding but 0 messages are sent out. 

There is also no way to see a chronological table of users being added to a site, and see who is authenticated and who is not and so to spot such issues quickly. 

Thanks in advance for any help. 

Using DNN 6.2.9