PRTG Manual: IMAP Sensor

The IMAP sensor monitors an email server using the Internet Message Access Protocol (IMAP).

The sensor can show the following:

IMAP Sensor

IMAP Sensor

Remarks

Add Sensor

The Add Sensor dialog appears when you manually add a new sensor to a device. It only shows the setting fields that are required for creating the sensor. Therefore, you do not see all setting fields in this dialog. You can change (nearly) all settings in the sensor's Settings tab later.

Sensor Settings

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

icon-i-round-blueUsually, a sensor connects to the IP Address or DNS Name of the parent device on which you created the sensor. See the device settings for details. For some sensors, you can explicitly define the monitoring target in the sensor settings. See below for details on available settings.

Basic Sensor Settings

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.

icon-i-round-blueIt 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).

Default Tags

imapsensor, mailsensor

Connectivity

Timeout (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).

Port

Enter the number of the port that the sensor uses to connect via IMAP. For non-secure connections, port 143 is ususally used. For Secure Sockets Layer (SSL) connections, it is usually port 993. The actual setting depends on the server you are connecting to. Enter an integer value. We recommend that you use the default value.

icon-i-round-blueIf you do not get a connection, try a different port number.

Security

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.

icon-i-round-blueIf 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.

icon-i-round-blueIf 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 Behavior

General Behavior

This sensor can additionally check the content of all incoming emails:

  • Check connectivity only, do not process emails (default): Only check the availability of the IMAP server and check if a login is successful. Do not process any emails in the IMAP email account.
  • Count emails in this mailbox: Count the emails in the defined mailbox.
  • Process emails in this mailbox: Log in to the IMAP email account and check the emails that it contains. Define further options below.

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.

icon-prtg-on-demandThis option is not available when the sensor runs on the hosted probe of a PRTG hosted by Paessler instance.

Authentication

Username

Enter a username for IMAP authentication. Enter a string.

Password

Enter a password for IMAP authentication. Enter a string.

icon-i-round-redThe password must not contain spaces or percent signs (%).

Folder Name

Enter the name of a folder in the mailbox (for example, the IMAP folder) that the sensor checks. The default value is Inbox. Unless you set a last message date check below, the sensor always looks at all emails contained in the mailbox.

icon-i-round-redEnsure that you do not manually edit emails in this mailbox with a different email client because this can result in malfunctions of this sensor's email identification.

Filter Emails in Inbox

icon-i-round-blueThis settings section is only visible if you choose to process the emails in the mailbox.

Only Include Emails with Matching "From"

Define if you want to check the "From" field of the emails:

  • Do not check (default): Do not process this field in emails.
  • Check using simple string search: Process this field in emails using a simple string in plain text.
  • Check using regular expression: Process this field in emails using a regular expression (regex).

When using a search, the sensor scans all emails from the newest to the oldest.

icon-i-round-bluePRTG supports Perl Compatible Regular Expression (PCRE) regex. You cannot use regex options or flags. For more details, see section Regular Expressions.

icon-i-round-redThe sensor finishes the scan with the first match. This means that after it has found a match in one email, the sensor does not perform any further checks in older emails.

Search for

This field is only visible if you enable a "from" check above. Enter an email address or a regular expression that the "From" field of the email must contain or match.

Only Include Emails with Matching "Subject"

Define if you want to check the "Subject" field of the emails:

  • Do not check (default): Do not process the subject of emails.
  • Check using simple string search: Process the subject of emails using a simple string in plain text.
  • Check using regular expression: Process the subject of emails using a regex.

When using a search, the sensor scans all emails from the newest to the oldest.

icon-i-round-bluePRTG supports Perl Compatible Regular Expression (PCRE) regex. You cannot use regex options or flags. For more details, see section Regular Expressions.

icon-i-round-redThe sensor finishes the scan with the first match. This means that after it has found a match in one email, the sensor does not perform any further checks in older emails.

Search for

This field is only visible if you enable a "subject" check above. Enter a simple string in plain text or a regular expression that the "Subject" field of the email must contain or match.

Only Include Emails with Matching Email Body

Define if you want to check the email body of the emails:

  • Do not check (default): Do not process the email body.
  • Check using simple string search: Process the email body using a simple string in plain text.
  • Check using regular expression: Process the email body using a regex.

When using a search, the sensor scans all emails from the newest to the oldest.

icon-i-round-bluePRTG supports Perl Compatible Regular Expression (PCRE) regex. You cannot use regex options or flags. For more details, see section Regular Expressions.

icon-i-round-redThe sensor finishes the scan with the first match. This means that after it has found a match in one email, the sensor does not perform any further checks in older emails.

Search for

This field is only visible if you enable checking the email body above. Enter a simple string in plain text or a regular expression that the body of the email must contain or match.

Only Include Recent Emails

Define if you want to check all emails in the mailbox or only mails that were received during the last few hours:

  • Do not check message age (default): Always check all emails that the mailbox contains.
  • Emails must be younger than: Only check emails that were received during the last few hours. Define below.

Maximum Age in Hours

This field is only visible if you enable the message age check above. Enter the maximum age in hours. The sensor only processes emails that are younger. Enter an integer value.

If No Email Matches the Above Filters

Define which status the sensor shows if it does not find any email in the mailbox that matches the defined filters:

  • Set sensor to up status (default)
  • Set sensor to warning status
  • Set sensor to down status

Message

This field is only visible if you define a Warning or Down status as no matching behavior above. Define the message that the sensor shows if it did not find any matching emails.

Validate Latest Email

icon-i-round-blueThis settings section is only visible if you choose to process the emails in the mailbox.

icon-i-round-redThe sensor only validates the latest email that matches the filters above. If the sensor does not find a matching email, it does not perform any email validation.

For the Latest Email that Matches, Set Sensor to "Warning" Status

Define in which cases the sensor shows a Warning status:

  • Never (default): Never set this sensor to a Warning status based on email content.
  • Always: Always set this sensor to a Warning status if any emails could be identified.
  • If subject contains: Set the sensor to a Warning status if the subject of the found email contains the search text you define below.
  • If subject does not contain: Set the sensor to a Warning status if the subject of the found email does not contain the search text you define below.
  • If email body contains: Set the sensor to a Warning status if the body of the found email contains the search text you define below.
  • If email body does not contain: Set the sensor to a Warning status if the body of the found email does not contain the search text you define below.

Search Method

This setting is only visible if you select an "if" condition above. Define the method with which you want to search for the respective condition:

  • Simple string search: Search the email subject or body with a simple string in plain text.

icon-i-round-blueThe characters * and ? work as placeholders. * stands for no number or any number of characters and ? stands for exactly one character (as known from the Windows search). You cannot change this behavior. The literal search for these characters is only possible with a regular expression.

  • Regular expression: Search the email subject or body with a regex.

icon-i-round-bluePRTG supports Perl Compatible Regular Expression (PCRE) regex. You cannot use regex options or flags. For more details, see section Regular Expressions.

Search String

This setting is only visible if you select an "if" condition above. Define the string that you want to search the email subject or body for. You can enter a simple string in plain text or a regular expression.

icon-i-round-redThe search string must be case sensitive.

Warning Message

This setting is only visible if you select a "warning" condition above. Define the message that the sensor shows for a Warning status.

Based on Message Age, Set Sensor to "Warning" Status

Define if you want to check the age of the latest matching email in the mailbox:

  • Never (default): Do not check the age of the email.
  • If email is older than: Set the sensor to a Warning status if the found email is older than you define below.

Message Age in Hours

This field is only visible if you enable the message age check above. Enter the maximum age in hours. If the processed email is older, the sensor shows a Warning status. Enter an integer value.

icon-i-round-redEnsure you do not manually edit emails in this mailbox with a different email client because this can result in malfunctions of the message age check.

For the Latest Email that Matches, Set Sensor to "Down" Status

Define in which cases the sensor shows a Down status:

  • Never (default): Never set this sensor to a Down status based on email content.
  • Always: Always set this sensor to a Down status if any emails could be identified.
  • If subject contains: Set the sensor to a Down status if the subject of the found email contains the search text you define below.
  • If subject does not contain: Set the sensor to a Down status if the subject of the found email does not contain the search text you define below.
  • If email body contains: Set the sensor to a Down status if the body of the found email contains the search text you define below.
  • If email body does not contain: Set the sensor to a Down status if the body of the found email does not contain the search text you define below.

Search Method

This setting is only visible if you select an "if" condition above. Define the method with which you want to search for the respective condition:

  • Simple string search: Search the email subject or body using a simple string in plain text.

icon-i-round-blueThe characters * and ? work as placeholders. * stands for no number or any number of characters and ? stands for exactly one character (as known from the Windows search). You cannot change this behavior. The literal search for these characters is only possible with a regular expression.

  • Regular expression: Search the email subject or body with a regex.

icon-i-round-bluePRTG supports Perl Compatible Regular Expression (PCRE) regex. You cannot use regex options or flags. For more details, see section Regular Expressions.

Search String

This setting is only visible if you enable an "if" condition above. Define the string that you want to search the email subject or body for. You can enter a simple string in plain text or a regular expression.

icon-i-round-redThe search string must be case sensitive.

Error Message

This setting is only visible if you select a "down" condition above. Define the message that the sensor shows for a Down status.

Sensor Display

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.

icon-i-round-blueYou 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.
    icon-i-round-blueThis 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.

Inherited Settings

By default, all of the following settings are inherited from objects that are higher in the hierarchy and should be changed there if necessary. Often, best practice is to change them centrally in the root group settings. For more information, see section Inheritance of Settings. To change a setting for this object only, disable inheritance by clicking the button next to inherit from under the corresponding setting name. You then see the options described below.

Scanning Interval

Click inherited_settings_button 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.

icon-i-round-blueSensors 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.

icon-i-round-blueIf you define error limits for a sensor's channels, the sensor immediately shows a Down status. No "wait" option applies.

icon-i-round-blueIf a channel uses lookup values, the sensor immediately shows a Down status. No "wait" options apply.

Schedules, Dependencies, and Maintenance Window

icon-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 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.

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

icon-i-round-blueSchedules 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.

icon-i-round-blueTo 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.

icon-i-round-blueTo 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.

icon-i-round-redThis 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.

Access Rights

Click inherited_settings_button 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.

icon-square-cyanFor more details on access rights, see section Access Rights Management.

More

icon-square-blueKNOWLEDGE BASE

How can I monitor my backup software to be sure backup succeeded last night?

My IMAP sensor does not process HTML emails correctly using regex. What can I do?

Can I analyze multipart emails using the IMAP sensor?

My IMAP sensor does not find emails when I check for message date. What can I do?

Edit Channels

To change display settings, spike filtering, and limits, switch to the sensor's Overview tab and click the gear icon of a specific channel. For detailed information, see section Sensor Channel Settings.

Notification Triggers

Click the Notification Triggers tab to change notification triggers. For detailed information, see section Sensor Notification Triggers Settings.

Others

For more general information about settings, see section Object Settings.

Sensor Settings Overview

For information about sensor settings, see the following sections: