The issue has been resolved and notifications are sending promptly for all users. The retries on past failed messages are going through now and will be all caught up in the next couple of minutes.
We are currently experiencing errors sending notifications for some of our OEM Partner sites through our default SMTP relay service provider. The errors show as failed inside the portal. Once our SMTP relay service provider is able to process the messages these failed messages will be re-sent.
Note: This does not affect end users of the iMonnit portal.