PRTG Manual: SMTP&POP3 Round Trip Sensor

Sensor Name

Enter a meaningful 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.

Parent Tags

Shows tags that this sensor inherits from its parent device, group, and probe. This setting is shown for your information only and cannot be changed here.

Tags

Enter one or more tags, separated by spaces or commas. You can use tags to group sensors and use tag–filtered views later on. Tags are not case sensitive. We recommend that you use the default value.

There are default tags that are automatically predefined in a sensor's settings when you add a sensor. See section Default Tags below.

You can add additional tags to the sensor if you like. Other tags are automatically inherited from objects further up in the device tree. These are visible above as Parent Tags.

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

Priority

Select a priority for the sensor. This setting determines where the sensor is placed in sensor lists. A sensor with a top priority is at the top of a list. Choose from one star (low priority) to five stars (top priority).

From

Specify the email address of the email's sender. Enter a valid email address.

To

Specify the address that PRTG sends the emails to. Enter a valid email address.

You can only enter one email address.

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.

In this step, you configure how PRTG sends the emails. The sensor uses the IP Address/DNS Name of its parent device (an SMTP server).

Port

Enter the number of the port that the sensor uses to send an email via SMTP.

For non-secure connections, port 25 is usually used, for Secure Sockets Layer (SSL)/Transport Layer Security (TLS) connections, port 465 or 587. The actual setting depends on the server you connect to. Enter an integer value. We recommend that you use the default value.

If you do not get a connection, try a different port number.

Timeout for SMTP Connection (Sec.)

Enter a timeout in seconds for the request. If the reply takes longer than this value, the sensor cancels the request and shows a corresponding error message. Enter an integer value. The maximum value is 900 seconds (15 minutes).

SMTP Authentication Type

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

• None: Do not use any authentication method.
• Username/Password: Authenticate against the SMTP server via username and password.

Username

This field is only visible if you enable Username/password above. Enter a username for SMTP authentication. Enter a string.

Password

This field is only visible if you enable Username/password above. Enter a password for SMTP authentication. Enter a string.

Additional Text for Email Subject

PRTG automatically creates the subject part of the round trip email. It consists of the string PRTG Roundtrip Mail:, followed by a unique globally unique identifier (GUID) to correctly identify the email in the POP3 mailbox, for example, PRTG Roundtrip Mail: {5E858D9C-AC70-466A-9B2A-55630165D276}.

Use this field to place your custom text before the automatically created text.

SMTP Specific

Define the security level for the sensor connection:

• Use Transport-Level Security if available using StartTLS (default): Try to connect to the server using Transport Layer Security (TLS) and StartTLS. If the server does not support this, the sensor tries to connect without encryption.
• Use Transport-Level Security if available: Try to connect to the server using TLS. If the server does not support this, the sensor tries to connect without encryption.
• Enforce Transport-Level Security using StartTLS: Try to connect to the server using TLS and StartTLS. If the server does not support this, the sensor shows a Down status.
• Enforce Transport-Level Security: Try to connect to the server using TLS. If the server does not support this, the sensor shows a Down status.

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

If the sensor uses TLS without 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.

In this step, you configure how to receive the sent emails.

IP Address/DNS Name

Specify the POP3 server. Enter a valid IP address or Domain Name System (DNS) name.

Port

Specify the port that the sensor uses for the POP3 connection.

For non-secure connections, port 110 is usually used, for SSL/TLS connections port 995. The actual setting depends on the server you are connecting to. Enter an integer value. We recommend that you use the default value.

If you do not get a connection, try a different port number.

Connection Interval (Sec.)

Enter the number of seconds the sensor waits between two connections to the POP3 server. PRTG continuously checks the mailbox in this scanning interval until the email arrives. Enter an integer value.

Maximum Trip Time (Sec.)

Enter the number of seconds an email may take to arrive in the POP3 mailbox. PRTG continuously checks the mailbox in the interval that you specify above until the email arrives. If it does not arrive within the maximum trip time, the sensor triggers an error message. Enter an integer value.

POP3 Authentication Type

Select the kind of authentication for the POP3 connection:

• Without Login: Only monitor the connection to the POP3 server.
• Username and Password: Log in to the POP3 server with username and password. (This is a simple login. It is not secure.)
• 128-bit MD5 hash value (APOP): Send the password in an encrypted form using APOP. This option must be supported by the POP3 server you connect to.

Username

This field is only visible if you enable an option with login above. Enter a username for POP3 authentication. Enter a string.

Password

This field is only visible if you enable an option with login above. Enter a username for POP3 authentication. Enter a string.

POP3 Specific

Define the security level for the sensor connection:

• Use Transport-Level Security if available using StartTLS (default): Try to connect to the server using Transport Layer Security (TLS) and StartTLS. If the server does not support this, the sensor tries to connect without encryption.
• Use Transport-Level Security if available: Try to connect to the server using TLS. If the server does not support this, the sensor tries to connect without encryption.
• Enforce Transport-Level Security using StartTLS: Try to connect to the server using TLS and StartTLS. If the server does not support this, the sensor shows a Down status.
• Enforce Transport-Level Security: Try to connect to the server using TLS. If the server does not support this, the sensor shows a Down status.

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

If the sensor uses TLS without 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.

Sensor Result

Define what PRTG does with the sensor results:

• Discard sensor result: Do not store the sensor result.
• Write sensor result to disk (file name: Result of Sensor [ID].txt): Store the last result received from the sensor to the \Logs\sensors subfolder of the PRTG data directory on the probe system (master node, if in a cluster). File names: Result of Sensor [ID].txt and Result of Sensor [ID].Data.txt. This is for debugging purposes. PRTG overwrites these files with each scanning interval.

This option is not available when the sensor runs on the hosted probe of a PRTG hosted by Paessler instance.

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 the pin symbol of a channel 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.
  This option cannot be used in combination with manual Vertical Axis Scaling (available in the channel settings).

Stack Unit

This field 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.

Click to interrupt the inheritance. See section Inheritance of Settings for more information.

Scanning Interval

Select a scanning interval (seconds, minutes, or hours). The scanning interval determines the amount of time that the sensor waits between two scans. You can change the available intervals in the system administration on PRTG on premises installations.

If a Sensor Query Fails

Define the number of scanning intervals that the sensor has time to reach and check a device again in case a sensor query fails. Depending on the option that you select, the sensor can try to reach and check a device again several times before the sensor shows a Down status. This can avoid false alarms if the monitored device only has temporary issues. For previous scanning intervals with failed requests, the sensor shows a Warning status. Choose from:

• Set sensor to down immediately: Set the sensor to a Down status immediately after the first failed request.
• Set sensor to warning for 1 interval, then set to down (recommended): Set the sensor to a Warning status after the first failed request. If the following request also fails, the sensor shows an error.
• Set sensor to warning for 2 intervals, then set to down: Set the sensor to a Down status only after three consecutively failed requests.
• Set sensor to warning for 3 intervals, then set to down: Set the sensor to a Down status only after four consecutively failed requests.
• Set sensor to warning for 4 intervals, then set to down: Set the sensor to a Down status only after five consecutively failed requests.
• Set sensor to warning for 5 intervals, then set to down: Set the sensor to a Down status only after six consecutively failed requests.

Sensors that monitor via Windows Management Instrumentation (WMI) always wait at least one scanning interval before they show a Down status. It is not possible to immediately set a WMI sensor to a Down status, so the first option does not apply to these sensors. All other options can apply.

If you define error limits for a sensor's channels, the sensor immediately shows a Down status. No "wait" option applies.

If a channel uses lookup values, the sensor immediately shows a Down status. No "wait" options apply.

You cannot interrupt the inheritance for schedules, dependencies, and maintenance windows. The corresponding settings from the parent objects are always active. However, you can define additional settings here. They are active at the same time as the parent objects' settings.

Schedule

Select a schedule from the list. Schedules can be used to monitor for a certain time span (days or hours) every week.

You can create schedules, edit schedules, or pause monitoring for a specific time span. For more information, see section Account Settings—Schedules.

Schedules are generally inherited. New schedules are added to schedules that you already set up, so all schedules are active at the same time.

Maintenance Window

Specify if you want to set up a one-time maintenance window. During a maintenance window, the selected object and all child objects are not monitored. They are in a Paused status instead. Choose between:

• Not set (monitor continuously): No maintenance window is set and monitoring is always active.
• Set up a one-time maintenance window: Pause monitoring within a maintenance window. You can define a time span for a monitoring pause below and change it even for an active maintenance window.

To terminate an active maintenance window before the defined end date, change the time entry in Maintenance Ends to a date in the past.

Maintenance Begins

This field is only visible if you enable Set up a one-time maintenance window above. Use the date time picker to enter the start date and time of the maintenance window.

Maintenance Ends

This field is only visible if you enable Set up a one-time maintenance window above. Use the date time picker to enter the end date and time of the maintenance window.

Dependency Type

Define a dependency type. You can use dependencies to pause monitoring for an object depending on the status of a different object. You can choose from:

• Use parent: Use the dependency type of the parent object.
• Select a sensor: Use the dependency type of the parent object. Additionally, pause the current object if a specific sensor is in a Down status or in a Paused status caused by another dependency.

• Master sensor for parent: Make this sensor the master object for its parent device. The sensor influences the behavior of its parent device: If the sensor is in a Down status, the device is paused. For example, it is a good idea to make a Ping sensor the master object for its parent device to pause monitoring for all other sensors on the device in case the device cannot even be pinged. Additionally, the sensor is paused if the parent group is paused by another dependency.

To test your dependencies, select Simulate Error Status from the context menu of an object that other objects depend on. A few seconds later, all dependent objects are paused. You can check all dependencies under Devices | Dependencies in the main menu bar.

Dependency

This field is only visible if you enable Select a sensor above. Click the Search button and use the object selector to select a sensor on which the current object will depend.

Dependency Delay (Sec.)

This field is only visible if you enable Select a sensor above. Define a time span in seconds for dependency delay.

After the master sensor for this dependency comes back to an Up status, monitoring of the dependent objects is additionally delayed by the defined time span. This can prevent false alarms, for example, after a server restart, by giving systems more time for all services to start up. Enter an integer value.

This setting is not available if you set this sensor to Use parent or to be the Master sensor for parent. In this case, define delays in the parent device settings or in its parent group settings.

Click to interrupt the inheritance. See section Inheritance of Settings for more information.

User Group Access

Define the user groups that have access to the sensor. You see a table with user groups and group access rights. The table contains all user groups in your setup. For each user group, you can choose from the following group access rights:

• Inherited: Inherit the access rights settings of the parent object.
• No access: Users in this user group cannot see or edit the sensor. The sensor neither shows up in lists nor in the device tree.
• Read access: Users in this group can see the sensor and view its monitoring results. They cannot edit any settings.
• Write access: Users in this group can see the sensor, view its monitoring results, and edit its settings. They cannot edit its access rights settings.
• Full access: Users in this group can see the sensor, view its monitoring results, edit its settings, and edit its access rights settings.

For more details on access rights, see section Access Rights Management.