mailcow (beta)

Whether the mail server is delivering: stopped containers, the size and age of Postfix’s queue, the volume holding the mailboxes and mailboxes close to their quota.

Beta

Written from the vendor’s API documentation and tested against realistic recorded-style responses, not yet against a live instance. Tell us what you see.

Network ports to open

From the DumbMonit server (or its relay agent) to the device:

Port	Protocol	Purpose
443	TCP	API (HTTPS, default)
80	TCP	Only with the http scheme option

The failure worth watching: one stopped container in a stack of twenty. rspamd down means no spam filtering, Dovecot down means no reading, Postfix down means no delivery, and the web interface still opens. A mailbox at its quota gets its incoming mail refused with nothing shown to the sender’s admin.

What it watches

All metrics are prefixed dumbmonit_mailcow_.

Metric	What	Labels
version_info	value 1	version
containers_total, containers_running	mailcow containers, and those running
container_up	1 per container while running (at most 32)	container
vmail_used_percent	the volume holding the mailboxes
queue_messages, queue_oldest_seconds	messages in Postfix’s queue and the age of the oldest
mailboxes_total, mailboxes_inactive, mailboxes_near_quota	mailboxes; deactivated ones; those at 90% of their quota or more
mailbox_quota_percent	mailboxes at 80% or more of their quota, at most 32	mailbox
scrape_errors	calls that failed on the last probe

The built-in rules that apply: mailcow container down, mailcow mail queue stuck, mailcow mail volume almost full, mailcow mailbox near quota, plus Monitor unreachable.

Create a read-only API key in mailcow

1. In mailcow, open System → Configuration → Access → API and find the Read-only access section.

2. Tick Activate API, add DumbMonit’s IP address to the allowed addresses and save.

3. Copy the read-only key, then enter mailcow’s address in DumbMonit and paste it.

Warning

mailcow only answers the addresses allowed on its API page: if DumbMonit reaches it through NAT or a relay agent, allow that address instead.

Credentials

Credential	Fields
API key	Sent in the X-API-Key header.

Address: a host name (mail.example.com), host:port, or a full URL. Mailbox names are published only for mailboxes close to their quota. Options: protocol (HTTPS by default), port (443), certificate check and request timeout (15 s).