How to create a notification email re: Volume Monitoring

There's a Canned (Out-of-the-box) alert "Alert me when the free space of a volume is less than 5%" that you can copy and use as a template.  just change 5 to 10.

Or are you asking about wanting to insert something in the E-Mail alert itself?

Have you been doing something similar to step 8 below?

https://support.solarwinds.com/Success_Center/Network_Performance_Monitor_(NPM)/Volume_alert_setup_

Steps

1. Login to your Web Console with full Admin rights.
2. Go to Home tab > Alerts > Click Manage Alerts.
3. Click Add new alert.
4. Under the Properties tab – Enter a name for the alert and description, then click Next.
5. Under the Trigger Condition tab – put the “I want to alert on” VOLUME.

   All Child conditions must be satisfied (AND)

                   Volume  Percent USED    is greater than or equal to 75%

                   **Condition must exist for more than (1 Minute).

6. Leave the Reset Condition tab empty.

7. Under Time of Day, leave it at default.

8. Go to Trigger Action > Add Action > Send Email /Page.
   Put the name of the Action
   Set the Email address
   Message Part:
   Click insert Variable to use for information on what to query. Samples are:
                    Node Name: ${N=SwisEntity;M=Node.Caption}
                    Volume Name ${N=SwisEntity;M=FullName}
                    Space Used: ${N=SwisEntity;M=VolumePercentUsed}
                    Time stamp: ${N=Generic;M=DateTime;F=DateTime}

9. Click Next to submit.
   Reset Action – just do the reverse of the Trigger action. You may select Send Email/Page, just make sure you change the title of the email or put an indicator that this email is for reset action notification.

10. Click Submit to Save.