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The basic primary function of this check is to log in to an IMAP or POP3 mailbox to monitor whether or not the login is possible. An extended feature is , that the check can fetch all (or just some) from the mailbox and forward them as events to the Event Console.

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  1. Setup → Services → HTTP, TCP, EMail, ... → Check Email → Add Rule

    1. Service description

      1. Here you can type in a service description. Please make sure that ensure this is unique per host and does not collide with other services.

    2. Mail Receiving

      1. Here you You can select if you want to check your IMAP or POP3 login. You need It would be best to have your login credentials for your E-Mail Email Mailbox.


    3. Forward emails as events to Event Console

      1. Forwarding Method

        • Here you You can select if you want to send the events either to the EC Event Console or to a remote syslog host. If you want to send the events to the local EC, we would recommend using the spooling mechanism.
          By using the spooling mechanism, the
          The check will store all collected events in one file in ~/var/mkeventd/spool using the spooling mechanism.

          Code Block
          languagebash
          themeRDark
          OMD[mysite]:~$ ll ~/var/mkeventd/spool/
          
          total 3600
          
          -rw-rw---- 1 mysite mysite 79124 Dec 7 15:36 mysite_407343_1607351778
          
          -rw-rw---- 1 mysite mysite 79124 Dec 7 15:37 mysite_408329_1607351841
          
          


      2. Only process mails with matching subject

        1. Use this option to not process all messages found in the inbox but only those whose subject matches the given regular expression. The text entered here is handled as a regular expression pattern. The pattern is matched from the beginning. Add a tailing $ to change it to a whole text match. The match is performed case-sensitive. Read more about regular expression matching in Checkmk in our official user official guide.
          .

          1. You need to be aware that a subject field could contain line breaks. This is depending on your mail client and mail gateway. To You could check the raw email to find out how many line breaks you have, you could check the raw email.

            .

          2. Now you can use regex platforms like regex101.com to create a regex.

            .

          3. For advanced debugging
            .
              1. Copy the plugin to the local path.

                Code Block
                languagebash
                themeRDark
                OMD[mysite]:~/lib/nagios/plugins$ cp check_mail ~/local/lib/nagios/plugins/

                .

              2. Add a print for the subject.

                Code Block
                languagebash
                themeRDark
                     for index, msg in sorted(mails.items()):
                         subject = msg.get('Subject', 'None')
                         print(subject)

                .

              3. Run the script manually.

                Code Block
                languagebash
                themeRDark
                OMD[mysite]:~/lib/nagios/plugins$ ./check_mail --pwstore=6@17@password_1 '--fetch-protocol=IMAP' '--fetch-server=imap.strato.de' '--fetch-tls' '--fetch-port=993' '--fetch-username=user@provider.com' '--fetch-password=*************' '--connect-timeout=10' '--forward-ec' '--match-subject=.*Incident.*\n.*assigned' 
                =?utf-8?Q?Incident_INC000000XXXX_has_bee?=
                 =?utf-8?Q?n_assigned_to_your_group_'XXXX=
                 =?utf-8?Q?XXXXX'_=XXXXX:_Comuni?=
                 =?utf-8?Q?XXXXX_-_Priority:_Low?=
                =?utf-8?Q?Incident_INC000000XXXX_has_bee?=
                 =?utf-8?Q?n_assigned_to_your_group_'XXXX=
                 =?utf-8?Q?XXXXX'_=XXXXX:_Comuni?=
                 =?utf-8?Q?XXXXX_-_Priority:_Low?=
                Forwarded 2 messages to event console | messages=2
                
                


      3. Events: Syslog facility

        1. Use this syslog facility for all created events.

      4. Events: Hostname

        1. Use this hostname for all created events instead of the name of the mailservermail server's name.

      5. Limit the length of the mail body.

        1. When forwarding mail from the mailbox to the event console, the body of the mail is limited to the given number of characters.

      6. Cleanup messages

        1. The handled messages (see subject matching) can be cleaned up by either deleting them or moving them to a subfolder. By default, nothing is cleaned up.




Debugging

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Event Console Log

In the log of the EC Event Console, you can see the processing messages from the spool file:

Code Block
languagebash
themeRDark
title~/var/log/mkeventd.log
2020-12-07 12:51:18,078 [20] [cmk.mkeventd.EventServer] Processing message '<21>Dec 7 12:51:17 localhost Checkmk EC: Checkmk EC|Email to EC of Checkmk!'

2020-12-07 12:51:18,079 [20] [cmk.mkeventd.EventServer] Parsed message:

application: Checkmk EC

core_host:

facility: 2

host: localhost

host_in_downtime: False

ipaddress:

pid: 0

priority: 5

text: Checkmk EC|Email to EC of Checkmk!

time: 1607341877.0


Execute active Check manually.

For debugging reasons, it could be useful helpful to run the check manually. Therefore, you need to open the service site of the E-Mail Email service and search for 'Service check command'. Now you can use the command for executing the check manually.

...

Code Block
languagebash
themeRDark
title~/lib/nagios/plugins
OMD[mysite]:~/lib/nagios/plugins$ ./check_mail --pwstore=6@11@strato '--protocol=IMAP' '--server=imap.provider.de' '--ssl' '--port=993' '--username=user@provider.com' '--password=*************' '--forward-ec' '--forward-method=spool:' '--match-subject=Checkmk EC' '--forward-facility=2' '--forward-host=localhost' '--cleanup=delete'
OK - Forwarded 0 messages to event console | messages=0

.

For a detailed log, you can use --debug at the end of the command:

Code Block
languagebash
themeRDark
OMD[mysite]:~$ ~/lib/nagios/plugins/check_mail --pwstore=6@11@strato '--protocol=IMAP' '--server=imap.provider.de' '--ssl' '--port=993' '--username=user@provider.com' '--password=*************' '--forward-ec' '--forward-method=spool:' '--match-subject=Checkmk EC' '--forward-facility=2' '--forward-host=localhost' '--cleanup=delete' --debug

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For more information, you can use --help

Code Block
languagebash
themeRDark
OMD[mysite]:~$ ~/lib/nagios/plugins/check_mail -h-help

.

One alternative:

Code Block
languagebash
themeRDark
OMD[mysite]:~$ lq "GET services\nColumns:host_name description check_command_expanded\nFilter: host_name = mysite\nFilter: description = Email"
localhost;Email;check_mk_active-mail!--pwstore=6@11@cmkmail '--protocol=IMAP' '--server=imap.strato.de' '--ssl' '--port=993' '--username=user@provider.com' '--password=****************' '--forward-ec' '--forward-method=spool:' '--forward-facility=2' '--forward-host=localhost'

OMD[mysite]:~$ cd ~/lib/nagios/plugins/

OMD[mysite]:~/lib/nagios/plugins$ ./check_mail --pwstore=6@11@cmkmail '--protocol=IMAP' '--server=imap.strato.de' '--ssl' '--port=993' '--username=user@provider.com' '--password=****************' '--forward-ec' '--forward-method=spool:' '--forward-facility=2' '--forward-host=localhost' --debug

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