Check manual page of check_mailboxes

IMAP Mailboxes

Included in	All Checkmk editions
Source Code License	Open Source
Supported Agents	Active

This active check logs into an IMAP or EWS account and optionally monitors the age of the oldest or newest mail as well as the total count of mails in one or multiple mailboxes.

There is a caveat though: Many mailservers don't support retrieving mails sorted by age and it would be very costy (in terms of traffic and check time) to retrive all mails. To work around this, the check retrieves a configurable number of the least recently and most recently modified mails from the server and checks the age of those. Unless mails get moved between mailboxes, the least recenly modified mail should also be the oldest one and the most recently modified mail should be the newest.

The following protocols and authentication methods are supported for fetching:

IMAP: Username/password (basic authentication).

EWS (Exchange Web Services): Username/password (basic authentication) or OAuth2 using ClientID, TenantID, and a client secret. When using EWS, the mailbox can optionally be identified by an email address (a.k.a. 'PrimarySmtpAddress') instead of the username.

Microsoft Exchange Online (Graph API): Microsoft Entra ID authentication via an OAuth2 connection. The connection can be configured directly in the check rule or managed centrally via Setup > Microsoft Entra ID connections and then referenced in the rule. In distributed environments, the OAuth2 connection can be created on the central site while the OAuth2 authentication process (redirect URI) is handled by a different remote site. The site used for the authentication redirect can be selected when configuring the OAuth2 connection.