PRTG Manual: SMTP Sensor

Sensor Name

Enter a name to identify the sensor. By default, PRTG shows this name in the device tree, as well as in alarms, logs, notifications, reports, maps, libraries, and tickets.

If the name contains angle brackets (<>), PRTG replaces them with braces ({}) for security reasons. For more information, see the Knowledge Base: What security features does PRTG include?

Parent Tags

The tags that the sensor inherits from its parent device, parent group, and parent probe.

This setting is for your information only. You cannot change it.

Tags

Enter one or more tags. Confirm each tag with the Spacebar key, a comma, or the Enter key. You can use tags to group objects and use tag-filtered views later on. Tags are not case-sensitive. Tags are automatically inherited.

It is not possible to enter tags with a leading plus (+) or minus (-) sign, nor tags with parentheses (()) or angle brackets (<>).

For performance reasons, it can take some minutes until you can filter for new tags that you added.

The sensor has the following default tags that are automatically predefined in the sensor's settings when you add the sensor:

• smtpsensor
• mailsensor

Priority

Select a priority for the sensor. This setting determines the position of the sensor in lists. The highest priority is at the top of a list. Choose from the lowest priority () to the highest priority ().

Timeout (Sec.)

Enter a timeout in seconds for the request. Enter an integer. The maximum timeout value is 900 seconds (15 minutes).

If the reply takes longer than this value, the sensor cancels the request and shows a corresponding error message.

Port

Enter the number of the port that the sensor uses to send an email via SMTP. The default port for unsecure connections is 25 and the default ports for secure connections are 465 or 587. The actual setting depends on the server that you connect to. Enter an integer.

We recommend that you use the default value.

If the connection is unsuccessful, try a different port number.

SMTP Authentication Method

Define if you want to use authentication for the SMTP connection:

• None: Do not use any authentication method.
• User name and password: Authenticate against the SMTP server via user name and password.

User Name

This setting is only visible if you select User name and password above. Enter a user name for SMTP authentication. Enter a string.

Password

This setting is only visible if you select User name and password above. Enter a password for SMTP authentication. Enter a string.

HELO Ident

Enter a server name for the HELO part of the mail protocol.

For some mail servers, the HELO identifier must be the valid principal host domain name for the client host. For more information, see SMTP RFC 2821.

If you leave this field empty, the value defaults to the computer name.

Only ASCII characters are allowed.

Transport-Level Security

Define how the sensor handles the security of the connection:

• Use transport-level security if available using StartTLS (default): Try to connect to the server via a Secure Sockets Layer (SSL)/Transport Layer Security (TLS) secured connection and StartTLS. If the server does not support this, the sensor tries to connect without connection security.
• Use transport-level security if available: Try to connect to the server via an SSL/TLS-secured connection. If the server does not support this, the sensor tries to connect without connection security.
• Enforce transport-level security using StartTLS: Try to connect to the server via an SSL/TLS-secured connection and StartTLS. If the server does not support this, the sensor shows the Down status.
• Enforce transport-level security: Try to connect to the server via an SSL/TLS-secured connection. If the server does not support this, the sensor shows the Down status.

If the sensor connects to a server via StartTLS, the connection is first established without connection security. After the connection has been established, the sensor sends a certain command (StartTLS) over the unsecured connection to negotiate a secure connection via SSL/TLS.

If the sensor does not use StartTLS, the negotiation of a secure connection happens immediately (implicitly) so that no commands are sent in unencrypted plain text. If no secure connection is possible, no communication takes place.

Email Handling

Define the monitoring approach when connecting to the SMTP server:

• Do not send an email: Do not send an email, only connect to the SMTP server.
• Send an email: Send an email through the SMTP server. If there is an error when sending the email, this triggers an error message and the sensor changes to the Down status.

From

This setting is only visible if you select Send email above. Specify the address of the sender of the email. Enter a valid email address.

To

This setting is only visible if you select Send email above. Specify the address that PRTG sends the email to. Enter a valid email address.

If you define more than one recipient, separate the individual email addresses with commas.

Topic

This setting is only visible if you select Send email above. Specify the subject that the email contains. Enter a string or leave the field empty.

Content

This setting is only visible if you select Send email above. Specify the body that the email contains. Enter a string or leave the field empty.

Result Handling

Define what PRTG does with the sensor result:

• Discard result: Do not store the sensor result.

• Store result: Store the last sensor result in the \Logs\sensors subfolder of the PRTG data directory on the probe system. The file names are Result of Sensor [ID].txt and Result of Sensor [ID].Data.txt. This setting is for debugging purposes. PRTG overwrites these files with each scanning interval.

In a cluster, PRTG stores the result in the PRTG data directory of the master node.

Primary Channel

Select a channel from the list to define it as the primary channel. In the device tree, the last value of the primary channel is always displayed below the sensor's name. The available options depend on what channels are available for this sensor.

You can set a different primary channel later by clicking below a channel gauge on the sensor's Overview tab.

Graph Type

Define how different channels are shown for this sensor:

• Show channels independently (default): Show a graph for each channel.
• Stack channels on top of each other: Stack channels on top of each other to create a multi-channel graph. This generates a graph that visualizes the different components of your total traffic.
  You cannot use this option in combination with manual Vertical Axis Scaling (available in the channel settings).

Stack Unit

This setting is only visible if you enable Stack channels on top of each other as Graph Type. Select a unit from the list. All channels with this unit are stacked on top of each other. By default, you cannot exclude single channels from stacking if they use the selected unit. However, there is an advanced procedure to do so.

Downtime

In the channel table on the Overview tab, this channel never shows any values. PRTG uses this channel in graphs and reports to show the amount of time in which the sensor was in the Down status

Response Time

The response time

This channel is the primary channel by default.