backup template mailserver

[theborg72]

What I would like is to be able to take care of backups from mailcow. Since we have support for databases but not from email server, I think that would make it even more powerful.

[marcpope]

My recommendation: Just backup the various directories of the software, not sure if they'd run without some repair because borg wouldn't be application-aware and the files would be open but you could stop the server at 3am, back it up, then restart the server post backup with the hooks. that would probably be the best way. Since borg only backs up the changed blocks, it would likely be quick. Your night-owls might complain. If you wanted just a few seconds of downtime, if you are running on ZFS or a filesystem that supports snapshots, you could do a stop of the server, snapshot, then start it back up, then backup from the snapshot. This is what a lot of commercial apps do. post backup script, delete the snapshot.

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Mailcow Backup with BBS using ZFS Snapshots

This approach gives you consistent backups with only a few seconds of downtime:

1. Pre-backup script: Stop mailcow, take a ZFS snapshot, start mailcow back up
2. BBS/borg backs up from the snapshot (mailcow is running the whole time)
3. Post-backup script: Destroy the snapshot

Setup

Assumes mailcow is installed at /opt/mailcow-dockerized with data on a ZFS dataset called tank/mailcow mounted at /var/lib/mailcow.

Pre-backup script (/usr/local/bin/mailcow-backup-pre.sh):
#!/bin/bash
set -euo pipefail

MAILCOW_DIR="/opt/mailcow-dockerized"
ZFS_DATASET="tank/mailcow"
SNAP_NAME="bbs-backup"
SNAP_MOUNT="/mnt/mailcow-snap"

Stop mailcow (few seconds of downtime)

cd "$MAILCOW_DIR" && docker compose down

Take a point-in-time snapshot

zfs snapshot "${ZFS_DATASET}@${SNAP_NAME}"

Start mailcow back up immediately

cd "$MAILCOW_DIR" && docker compose up -d

Mount the snapshot read-only for borg to back up from

mkdir -p "$SNAP_MOUNT"
mount -t zfs -o ro "${ZFS_DATASET}@${SNAP_NAME}" "$SNAP_MOUNT" 2>/dev/null ||
zfs set mountpoint="$SNAP_MOUNT" "${ZFS_DATASET}@${SNAP_NAME}" 2>/dev/null || true

echo "Snapshot ready at $SNAP_MOUNT"

Post-backup script (/usr/local/bin/mailcow-backup-post.sh):
#!/bin/bash
set -euo pipefail

ZFS_DATASET="tank/mailcow"
SNAP_NAME="bbs-backup"
SNAP_MOUNT="/mnt/mailcow-snap"

Unmount and destroy the snapshot

umount "$SNAP_MOUNT" 2>/dev/null || true
zfs destroy "${ZFS_DATASET}@${SNAP_NAME}"
rmdir "$SNAP_MOUNT" 2>/dev/null || true

echo "Snapshot cleaned up"

BBS Configuration

1. Make both scripts executable: chmod +x /usr/local/bin/mailcow-backup-*.sh
2. In BBS, create a Shell Script Hook plugin config:
   - Pre-script: /usr/local/bin/mailcow-backup-pre.sh
   - Post-script: /usr/local/bin/mailcow-backup-post.sh
   - Abort on failure: checked
   - Timeout: 300 seconds
3. In your backup plan, set the backup directory to /mnt/mailcow-snap (the snapshot mount, not the live data)
4. Link the plugin config to the backup plan

How it works

• Mailcow is down for only the few seconds it takes to docker compose down, snapshot, docker compose up -d
• Borg backs up from the frozen snapshot — all files are consistent, no open file issues
• After borg finishes, the post-script destroys the snapshot
• Since borg deduplicates, subsequent backups only transfer changed blocks and are fast

Without ZFS

If you're not on ZFS, you can still use the same approach with simpler scripts that just stop/start mailcow:

Pre-backup: stop mailcow

cd /opt/mailcow-dockerized && docker compose down

Post-backup: start mailcow

cd /opt/mailcow-dockerized && docker compose up -d

Set your backup directory to /var/lib/mailcow (or wherever mailcow stores its data). Downtime will last for the entire backup duration, so schedule it during low-traffic hours.

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[theborg72]

like mailcow has a backup script in it. it's just in case you can get them to work together somehow. where borg triggers the mail script and picks it up when it's done. Maybe a little over complicated. Now you can go in and run the script first. You can run it in a cron task.

[marcpope]

You can easily do this with the Shell Script plugin today: