PRTG Manual: IMAP Sensor

SRP ciphers

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

Microsoft 365 mailboxes

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

IPv4

This sensor only supports IPv4.

Performance impact

This sensor has a medium performance impact.

Content checks

If you use content checks, we recommend that you use a dedicated IMAP account that is only checked by PRTG. Editing mails in the mailbox of the monitored IMAP account can lead to false alarms or malfunctions of this sensor.

Subfolder monitoring

This sensor might not work properly when monitoring subfolders of mailboxes. If it has to check subsequent emails with identical subjects, it might not recognize emails that come in later.

Daylight Saving Time

Emails that arrive during the Daylight Saving Time (winter time to summer time) change might not be processed properly. If you experience this issue, delete the respective emails.

Knowledge Base

• Knowledge Base: My IMAP sensor does not process HTML emails correctly using regex. What can I do?
• Knowledge Base: How can I monitor my backup software to be sure backup succeeded last night?
• Knowledge Base: Can I analyze multipart emails using the IMAP sensor?
• Knowledge Base: My IMAP sensor does not find emails when I check for message date. What can I do?

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

Specify the port that the sensor uses for the IMAP connection. The default port for unsecure connections is 143 and the default port for secure connections is 993. The actual setting depends on the server you connect to. Enter an integer.

We recommend that you use the default value.

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

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 Processing

Define if the sensor additionally checks the content of all incoming emails:

• 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 the mailbox: Count the emails in the mailbox.
• Process emails in the mailbox: Log in to the IMAP email account and check the emails that it contains. Define further options below.

Result Handling

Define what PRTG does with the sensor result:

• Discard result (default): 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.

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

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

User Name

Enter a user name for IMAP authentication. Enter a string.

Password

Enter a password for IMAP authentication. Enter a string.

The password must not contain spaces, percent signs (%), or the character combination !*.

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.

Make sure 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.

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).

In the search, the sensor scans all emails from the newest to the oldest.

PRTG supports Perl Compatible Regular Expression (PCRE) regex. For more information, see section Regular Expressions.

The sensor finishes the scan with the first match. This means that after it finds a match in one email, the sensor does not perform any further checks in older emails.

Search for

This setting is only visible if you select Check using simple string search or Check using regular expression above.

Enter the email address or the 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 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).

In the search, the sensor scans all emails from the newest to the oldest.

PRTG supports Perl Compatible Regular Expression (PCRE) regex. For more information, see section Regular Expressions.

The sensor finishes the scan with the first match. This means that after it finds a match in one email, the sensor does not perform any further checks in older emails.

Search for

This setting is only visible if you select Check using simple string search or Check using regular expression above.

Enter the simple string in plain text or the regex 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 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.

In the search, the sensor scans all emails from the newest to the oldest.

PRTG supports Perl Compatible Regular Expression (PCRE) regex. For more information, see section Regular Expressions.

The sensor finishes the scan with the first match. This means that after it finds a match in one email, the sensor does not perform any further checks in older emails.

Search for

This setting is only visible if you select Check using simple string search or Check using regular expression above.

Enter the simple string in plain text or the regex 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): 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 (Hours)

This setting is only visible if you select Emails must be younger than above.

Enter the maximum age in hours. The sensor only processes emails that are younger. Enter an integer.

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 above filters:

• Set sensor to up status (default): Show the Up status if the sensor does not find any email in the mailbox that matches the filters.
• Set sensor to warning status: Show the Warning status if the sensor does not find any email in the mailbox that matches the filters.
• Set sensor to down status: Show the Down status if the sensor does not find any email in the mailbox that matches the filters.

Message

This setting is only visible if you select Set sensor to warning status or Set sensor to down status above.

Define the message that the sensor shows if it does not find any matching emails.

Set Sensor to Warning Status

Define in which cases the sensor shows the Warning status:

• Never (default): Never show the Warning status because of email content.
• Always: Always show the Warning status if it could identify any emails.
• If subject contains: Show the Warning status if the subject of the email contains the Search String you define below.
• If subject does not contain: Show the Warning status if the subject of the email does not contain the Search String you define below.
• If email body contains: Show the Warning status if the body of the email contains the Search String you define below.
• If email body does not contain: Show the Warning status if the body of the email does not contain the Search String you define below.

Search Method

This setting is only visible if you select If subject contains, If subject does not contain, If email body contains, or If email body does not contain above.

Define the method with which you want to search for the respective condition:

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

The characters * and ? work as placeholders. * stands for no number or any number of characters and ? stands for exactly one character. You cannot change this behavior. The literal search for these characters is only possible with a regex.

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

PRTG supports Perl Compatible Regular Expression (PCRE) regex. For more information, see section Regular Expressions.

Search String

This setting is only visible if you select If subject contains, If subject does not contain, If email body contains, or If email body does not contain 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 regex.

Warning Message

This setting is only visible if you select a "warning" condition above.

Define the message that the sensor shows for the Warning status.

Set Sensor to Down Status

Define in which cases the sensor shows the Down status:

• Never (default): Never show the Down status based on email content.
• Always: Always show the Down status if any emails could be identified.
• If subject contains: Show the Down status if the subject of the found email contains the Search String you define below.
• If subject does not contain: Show the Down status if the subject of the found email does not contain the Search String you define below.
• If email body contains: Show the Down status if the body of the found email contains the Search String you define below.
• If email body does not contain: Show the Down status if the body of the found email does not contain the Search String you define below.

Search Method

This setting is only visible if you select If subject contains, If subject does not contain, If email body contains, or If email body does not contain above.

Define the method with which you want to search for the respective condition:

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

The characters * and ? work as placeholders. * stands for no number or any number of characters and ? stands for exactly one character. You cannot change this behavior. The literal search for these characters is only possible with a regex.

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

PRTG supports Perl Compatible Regular Expression (PCRE) regex. For more information, see section Regular Expressions.

Search String

This setting is only visible if you select If subject contains, If subject does not contain, If email body contains, or If email body does not contain 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 regex.

Error Message

This setting is only visible if you select Always, If subject contains, If subject does not contain, If email body contains, or If email body does not contain above.

Define the message that the sensor shows for the Down 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 the Warning status if the found email is older than you define below.

Message Age (Hours)

This setting is only visible if you select the message age check above.

Enter the maximum age in hours. If the processed email is older, the sensor shows the Warning status. Enter an integer.

Make sure 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.

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.

Available

The response time

This channel is the primary channel by default.

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

Email Count

The number of emails in the defined mailbox