PRTG Manual: SMTP Sensor

SRP ciphers

This sensor does not support Secure Remote Password (SRP) ciphers.

IPv4

This sensor only supports IPv4.

Performance impact

This sensor has a low performance impact.

Hosted probe

You cannot add this sensor to the hosted probe of a PRTG Hosted Monitor instance. If you want to use this sensor, add it to a remote probe device.

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 (default): 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: 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 (default): 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 (default): 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 an 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 an 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.

Subject

This setting is only visible if you select Send an 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 an 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 (default): Do not store the sensor result.
• Store result: Store the sensor result and the last response 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, PRTG displays the last value of the primary channel 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 this sensor shows different channels:

• 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 select Stack channels on top of each other above.

Select a unit from the list. PRTG stacks all channels with this unit 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.