PRTG Manual: SMTP&POP3 Round Trip Sensor

The SMTP&POP3 Round Trip sensor monitors the time it takes for an email to reach a Post Office Protocol version 3 (POP3) mailbox using the Simple Mail Transfer Protocol (SMTP). It sends an email using the parent device (an SMTP server) and then scans a dedicated POP3 mailbox until the email comes in.

i_round_blueThe SMTP&POP3 Round Trip sensor automatically deletes these emails from the mailbox as soon as PRTG has retrieves them. Emails only remain in the mailbox if a timeout or a restart of the PRTG core server occurs during sensor runtime.

SMTP&POP3 Round Trip Sensor

SMTP&POP3 Round Trip Sensor

i_square_cyanFor a detailed list and descriptions of the channels that this sensor can show, see section Channel List.

Sensor in Other Languages

Dutch: SMTP & POP3 Round Trip

French: SMTP & POP3 aller-retour

German: SMTP&POP3-Übermittlung

Japanese: SMTP&POP3 ラウンドトリップ

Portuguese: Ida e volta SMTP&POP3

Russian: Цикл SMTP и POP3

Simplified Chinese: SMTP 和 POP3 往返

Spanish: Ida y vuelta SMTP&POP3

Remarks

This sensor has a high performance impact. Use it with care. We recommend that you use no more than 200 sensors of this sensor type on each probe.

The parent device must be an SMTP server.

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

This sensor does not support Microsoft 365 mailboxes. If you want to monitor a Microsoft 365 mailbox, use the Microsoft 365 Mailbox sensor.

This sensor only supports the IPv4 protocol.

Use dedicated email accounts with this sensor. If you use more sensors of this type, make sure that each sensor uses its own email accounts.

Add Sensor

The Add Sensor dialog appears when you manually add a new sensor to a device. It only shows the settings that are required to create the sensor. You can change nearly all settings on the sensor's Settings tab after creation.

Basic Sensor Settings

Click the Settings tab of a sensor to change its settings.

Basic Sensor Settings

Basic Sensor Settings

Setting

Description

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.

i_round_blueIf 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

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

i_round_blueThis 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.

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

i_round_blueFor 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:

pop3sensor

roundtrip

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 (i_priority_1) to the highest priority (i_priority_5).

Email Settings

Email Settings

Email Settings

Setting

Description

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.

i_round_blueYou can only enter one email address.

HELO Ident

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

i_round_blueFor 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.

i_round_redOnly ASCII characters are allowed.

Step 1: Send Email Using Parent Device (SMTP Server)

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

Step 1: Send Email Using Parent Device (SMTP Server)

Step 1: Send Email Using Parent Device (SMTP Server)

Setting

Description

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.

i_round_blueWe recommend that you use the default value.

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

Timeout for SMTP Connection (Sec.)

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

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

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.

Additional Text for Email Subject

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

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

Connection Security

Connection Security

Connection Security

Setting

Description

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.

i_round_blueIf 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.

i_round_blueIf 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.

Step 2: Check a POP3 Mailbox until Email Arrives

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

Step 2: Check an IMAP Mailbox until Email Arrives

Step 2: Check an IMAP Mailbox until Email Arrives

Setting

Description

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. The default port for unsecure connections is 110 and the default port for secure connections is 995. The actual setting depends on the server you connect to. Enter an integer.

i_round_blueWe recommend that you use the default value.

i_round_blueIf the connection is unsuccessful, 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.

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.

POP3 Authentication Method

Select the authentication method for the POP3 connection:

Without login: Only monitor the connection to the POP3 server.

User name and password: Log in to the POP3 server with user name and password.
i_round_blueThis is a simple login. It is not secure.

128-bit MD5 hash value (APOP): Send the password in an encrypted form using APOP.
i_round_redThe POP3 server that you connect to must support this option.

User Name

This setting is only visible if you select User name and password or 128-bit MD5 hash value (APOP) above. Enter a user name for POP3 authentication. Enter a string.

Password

This setting is only visible if you select User name and password or 128-bit MD5 hash value (APOP) above. Enter a user name for POP3 authentication. Enter a string.

Connection Security

Connection Security

Connection Security

Setting

Description

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.

i_round_blueIf 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.

i_round_blueIf 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.

Debug Options

Debug Options

Debug Options

Setting

Description

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.

i_podThis option is not available when the sensor runs on the hosted probe of a PRTG Hosted Monitor instance.

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

Sensor Display

Sensor Display

Sensor Display

Setting

Description

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.

i_round_blueYou can set a different primary channel later by clicking b_channel_primary 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.
i_round_redYou 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.

Inherited Settings

By default, all of these settings are inherited from objects that are higher in the hierarchy. We recommend that you change them centrally in the root group settings if necessary. To change a setting for this object only, click b_inherited_enabled under the corresponding setting name to disable the inheritance and to display its options.

i_square_cyanFor more information, see section Inheritance of Settings.

Scanning Interval

Scanning Interval

Scanning Interval

i_square_cyanFor more information, see section Root Group Settings, section Scanning Interval.

Schedules, Dependencies, and Maintenance Window

i_round_blueYou 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 schedules, dependencies, and maintenance windows. They are active at the same time as the parent objects' settings.

Schedules, Dependencies, and Maintenance Window

Schedules, Dependencies, and Maintenance Window

i_square_cyanFor more information, see section Root Group Settings, section Schedules, Dependencies, and Maintenance Window.

Access Rights

Access Rights

Access Rights

i_square_cyanFor more information, see section Root Group Settings, section Access Rights.

Channel List

i_round_blueWhich channels the sensor actually shows might depend on the target device, the available components, and the sensor setup.

Channel

Description

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 (POP3)

The response time of the POP3 server in milliseconds (msec)

Response Time (SMTP)

The response time of the SMTP server in msec

Total

The sum of the response time of the SMTP server and the POP3 server in msec

i_round_blueThis channel is the primary channel by default.

More

i_square_blueKNOWLEDGE BASE

What security features does PRTG include?

https://kb.paessler.com/en/topic/61108