VMware ESXi and vSphere Cluster Management

Configure Email and SNMP Alarm Notifications in vCenter Server

Learn how to configure vCenter Server mail and SNMP receivers, attach notification actions to alarms, validate delivery, and troubleshoot missing alerts.

vCenter Server alarms monitor conditions in the vSphere inventory. When an alarm reaches a configured state or trigger condition, it can execute one or more actions, including sending an email or an SNMP trap.

The alarm definition and notification delivery are separate concerns. The alarm defines what is monitored and when its state changes. A notification action defines where information about that event is sent. Configure global mail or SNMP receiver settings first, then attach the appropriate action to each alarm that should notify administrators or an external monitoring platform.

What vCenter Server Alarm Notifications Do

An alarm evaluates a condition such as host health, virtual machine state, capacity, or another monitored property. Depending on the alarm configuration, it can perform an action when the condition is met, cleared, or changes state.

This lesson covers two notification mechanisms:

• Email: vCenter Server relays a message through an SMTP server to specified recipients.
• SNMP trap: vCenter Server sends an unsolicited SNMP notification to a configured SNMP receiver, such as a network-monitoring or event-correlation platform.

Configuring an SMTP server or SNMP receiver does not automatically notify anyone about every alarm. Each relevant alarm must have an email or SNMP action assigned to the required alarm state transition or trigger behavior.

Prerequisites

• A functioning vCenter Server inventory and permission to edit vCenter Server settings and alarm definitions.
• An accessible SMTP relay or mail server for email delivery.
• An SNMP management system or trap receiver that is reachable from vCenter Server.
• Network connectivity, DNS resolution when hostnames are used, and firewall rules that permit the relevant traffic.
• An existing alarm, or a plan for creating an alarm, whose actions will include a notification.

You should also understand basic vSphere alarms, alarm conditions, and state transitions. If permission changes are needed, review assigning permissions before starting.

Email and SNMP Notification Comparison

Configure Email Notification Settings

Mail settings are configured on the vCenter Server object. These global settings provide the SMTP information that email actions use when sending alarm messages.

1. Open the vSphere Web Client and select the vCenter Server object in the inventory.
2. Open Manage, then open the General settings area.
3. Select Edit settings.
4. Select the Mail section.
5. Enter the SMTP server hostname, which is the DNS name of the mail relay or server used to send messages.
6. Enter the sender account or sender address that should appear as the source of vCenter alarm emails.
7. Save the settings.

The sender identity should be recognizable and accepted by the organization’s mail relay. The SMTP server must be reachable from vCenter Server, and the relay must accept messages using the configured sender identity and its own delivery policy.

Mail Configuration Inputs

Configure SNMP Trap Receivers

An SNMP receiver is a monitoring server or collector that listens for traps. A trap receiver port is the network port on which that system accepts trap messages.

1. Select the vCenter Server object in the vSphere Web Client inventory.
2. Open Manage, then General, and select Edit settings.
3. Select SNMP Receivers.
4. Add a receiver using its hostname or network address and listening port.
5. Repeat the process for additional monitoring systems as required.
6. Save the receiver configuration.

vCenter Server supports up to four configured SNMP receivers. Keep the receiver list within that limit and confirm that every listed system is intended to receive vCenter alarm traps.

SNMP Receiver Capacity

Attach Notifications to an Alarm

Global delivery settings only make email and SNMP delivery possible. Notification actions must be attached to each relevant alarm definition.

1. Open the alarm definition creation or edit workflow for the intended inventory object or scope.
2. Define or review the alarm condition, thresholds, and trigger behavior.
3. Open the Actions page of the alarm definition wizard.
4. Add an email notification action and specify the intended recipient or recipients.
5. If an external monitoring platform is required, add an SNMP trap notification action.
6. Associate each action with the appropriate alarm state transition or trigger behavior, such as a warning or critical state.
7. Save the alarm definition.

For example, an alarm might send email when a condition enters a critical state, while an SNMP trap is sent for the same transition to allow centralized correlation. A clear-state notification can be useful, but adding actions to every transition can create unnecessary messages.

Practical Example: Email a Critical Operations Alert

1. Configure the organization’s SMTP relay in the vCenter Server Mail settings.
2. Use a recognizable sender address such as the organization’s vCenter alert identity.
3. Create or edit a virtual machine alarm for a meaningful critical condition.
4. On the alarm’s Actions page, add an email notification action.
5. Specify the operations distribution list as the recipient.
6. Associate the action with the critical alarm transition and save the alarm.
7. Trigger a safe test condition when operationally appropriate.
8. Confirm that the distribution list receives the message and that the sender and alarm details are correct.

The result is a direct administrator-facing email when the selected virtual machine condition occurs.

Practical Example: Send Host-Health Alarms to Monitoring

1. Identify the monitoring platform’s SNMP trap receiver hostname or address and listening port.
2. Add that system under SNMP Receivers in vCenter Server settings.
3. Create or edit a host-health alarm.
4. On the alarm’s Actions page, add an SNMP trap action.
5. Associate the action with the appropriate host-health state or trigger.
6. Save the alarm definition.
7. Generate or simulate a permitted test event and inspect the monitoring platform for the trap.

The monitoring platform should receive the vCenter alarm data and parse it according to its integration configuration.

Practical Example: Use Multiple Monitoring Destinations

Separate monitoring or management systems can be configured as SNMP receivers. Add each intended destination, keep the total at four or fewer, and assign SNMP actions only to alarms that need external visibility. Verify delivery to every destination rather than assuming that successful delivery to one receiver proves all receivers are reachable.

Validate Notification Behavior

1. Reopen the vCenter Server settings and confirm that the SMTP server, sender identity, SNMP receiver addresses, and ports were saved correctly.
2. Review the alarm definition’s Actions page to confirm that the expected email and/or SNMP action is present.
3. Check that each action is associated with the intended state transition or trigger behavior.
4. Use a controlled alarm condition when operationally safe. Avoid deliberately causing an outage or risking production workloads.
5. For email, verify receipt, sender identity, recipient addressing, message arrival, and any mail-relay processing.
6. For SNMP, verify receipt and parsing in the monitoring platform.
7. Review the alarm status and recent events when a notification is missing.

Operational Design Considerations

• Use email for administrator-facing alerts that need human attention.
• Use SNMP traps for centralized monitoring, event correlation, and automated operations workflows.
• Assign actions only to meaningful warning or critical states and conditions. Excessive notifications can hide important events.
• Use reliable, monitored SMTP and SNMP endpoints rather than temporary or unmanaged destinations.
• Document notification recipients, trap receivers, ownership, and escalation expectations.
• Review alarm scope and state transitions so the same condition does not generate duplicate notifications from overlapping alarms.

Troubleshooting Missing or Excessive Notifications

An Alarm Triggers but No Email Arrives

• Confirm that the alarm has an email action associated with the correct state transition.
• Verify the SMTP server hostname and configured sender account or address.
• Confirm that recipient addresses or distribution lists are correct.
• Check DNS resolution, network reachability, firewall policy, and SMTP relay acceptance from vCenter Server.
• Review alarm events to verify that the notification action was invoked.

SNMP Traps Do Not Appear in the Monitoring Platform

• Confirm that the alarm includes an SNMP trap action.
• Verify the configured receiver hostname or address and port.
• Confirm that the selected destination is one of the vCenter Server SNMP receivers.
• Check name resolution, routing, firewall rules, and receiver listener availability.
• Verify that the monitoring platform accepts and interprets traps from vCenter Server.

Only Some Alarms Generate Notifications

• Compare the Actions configuration of working and nonworking alarms.
• Check alarm state transitions and trigger conditions.
• Confirm that the alarm is enabled and attached to the intended inventory object or scope.
• Ensure that notification actions were saved after editing the alarm.

Too Many Notification Messages Are Generated

• Review alarm thresholds, sensitivity, and state-transition actions.
• Limit notifications to actionable warning or critical events.
• Use appropriate recipient groups and centralized SNMP correlation to reduce duplicate escalation.

Key Exam and Administration Notes

• The alarm defines the monitored condition; the notification action defines how and where an event is communicated.
• Global Mail settings require an SMTP server hostname and sender account or address.
• Global SNMP settings define receiver hostnames or addresses and ports.
• Up to four SNMP receivers can be configured.
• Email recipients and SNMP trap actions are assigned on the alarm definition wizard’s Actions page.
• Every alarm that requires notification must have its own applicable action configuration.

For broader alarm administration, see Alarms in vSphere, alarm trigger types, and acknowledging an alarm.