Nagios Support Forum

No you can use Sendmail or SMTP, the notification handlers depend on how you have your XI system set up. As Sreinhardt had pointed out, depending on if you are using Users, or Contacts within Nagios Xi you need to choose one or the other handler, as you saw in this case. Do you have additional contacts set up throughout your system or are you using Users for notifications?

I found the Users section under Admin. All settings look correct. I did have to remove the notify-host-by-email to get the settings to apply. Still no email notifications. I can still send and successfully receive a test email. I can no longer send custom notifications.

When you try to send the custom notification, are you choosing "Force" ?

Try removing the XI notifications if you are not receiving notifications, but were when using the older notify-host-by-email. You are correct though, you can only define one set of notification handlers and cannot have 2 for a single check. You can however use them separately for different checks.

No I am not choosing force. They actually don't work if I choose force. Just to recap here is where the status of my notifications currently stands:
After removing the notify-host-by-email I was able to configure the Notification Management under Admin>Users. This did not resolve the notifications but once this page was configured I am then able to add the notify-host-by-email back to the list and then I do start receiving notifications by email. However, with notify-host-by-email it then breaks the Notification Methods and Messages pages and I see the message "Nagios XI notification handlers are not defined for this account. XI notification handlers must be defined in the Core Config Manager for customized notification settings." Yet I am receiving notifications for the time being; just unable to edit these pages unless I remove notify-host-by-email and then add it back after I make the changes.

Thanks

You can use "contacts only" if you wish (instead of users), however, keep in mind that users can modify their notification preferences, while "contacts only" cannot. Please, review this document to learn more about users and contacts in XI.

Tip: Review your contacts' configurations, and compare the ones that work to the ones that don't.